If you’re weighing a trip and wondering about the weather in Ireland in September, you’ve picked a smart window. Early autumn overlaps the late summer months, delivering mild temperatures, generous daylight hours, and cultural events without peak-season stress. It’s classic shoulder season travel on the Emerald Isle: fewer crowds, better accommodation value, and enough blue skies to explore if you pack a waterproof jacket.

Quick Answer: Weather in Ireland in September at a Glance

• Average temperatures (nationwide): 10–17°C (50–63°F); cooler in the north and west, milder in the south and east.
• Average rainfall: roughly 60–100 mm depending on region; the Wild Atlantic Way and County Donegal see more showers.
• Daylight hours: about 12.5–13 hours in early September; ~11.5–12 by the end of the month.
• Sunshine: 4–5 hours/day on average; bright spells often follow short showers.
• Sea temperature: about 14–16°C; bracing but swimmable for experienced bathers.
• Wind: breezier along Atlantic and north coasts; calmer inland and in sheltered valleys.
• Bottom line: Mild, changeable, and comfortable for touring; an ideal time to visit if you stay flexible.

Average Temperatures in Ireland in September (By Region)

Ireland’s oceanic climate keeps temperatures moderate compared to continental Europe. The average temperature masks quick shifts, but it’s a reliable guide for visiting Ireland and building a weather-smart route.

Dublin and the East: Average Temperatures and Conditions

• Average temperature: 11–17°C; nights cool, afternoons mild, and wind is usually gentler than the west.
• What to expect: Pleasant city walking weather with long dry intervals and fewer squalls than the west.
• Trip tip: Spend a morning on foot in Phoenix Park and plan for cool evenings around Temple Bar and the city’s pubs with live music.

The West and Wild Atlantic Way (Galway, Clare, Mayo)

• Average temperatures: 10–16°C; wind on clifftops and headlands can lower the “feels like” temperatures.
• What to expect: A classic mix of sun and showers, dramatic light, and rainbows after fronts pass.
• Trip tip: If your tour follows the Wild Atlantic Way, carry a windproof layer and keep plans flexible to chase clear windows.

The South (Cork, Kerry)

• Average temperatures: 11–17°C; among the milder areas in September with gentle breezes.
• What to expect: Sheltered spots in Killarney National Park can feel warm on calm afternoons, especially after a shower clears.
• Trip tip: Boat trips by Ross Castle usually run unless winds are strong; reserve early on busy weekends.

The North and Northern Ireland (Donegal, Antrim)

• Average temperatures: 9–15°C; cooler and windier on exposed coasts and uplands.
• What to expect: Quick shifts from sun to shower; invigorating air along the Causeway Coastal Route and County Donegal’s beaches.
• Trip tip: Pack a warm mid-layer and a hooded waterproof jacket for cliff paths and coastal lookouts.

Inland and the Midlands

• Average temperatures: 9–16°C; calmer winds and slightly wider day–night swings.
• What to expect: Cool, misty mornings burning off to mild afternoons; ideal for cycling and exploring Irish history sites.
• Trip tip: Expect more dew and slick patches after rain; waterproof footwear keeps you comfortable on foot.

Rain, Sunshine, and Daylight Hours in September

You’ll encounter “sunshine-and-showers” rather than all-day deluges. Plan outdoor blocks around forecasts and keep one or two indoor options for the rainiest hours.

Average Rainfall and What Showers Feel Like

• East and Southeast (Dublin, Wicklow, Wexford): Lower average rainfall; showers are shorter with longer dry breaks.
• West and North (Galway, Mayo, Donegal): Higher average rainfall; showers visit more often, but many last 10–30 minutes.
• After fronts: Skies often clear with crisp visibility and patches of blue skies for photos.

Rainfall feel chart (relative scale, 1=lower, 5=higher)

• Dublin & East: 2–3
• South (Cork, Kerry): 3
• West (Galway, Clare): 4
• North & Northern Ireland: 4–5
• Midlands: 3

Daylight Hours, Sunrise, and Sunset

At the beginning of September, you’ll have long days for touring and hikes with safe buffers before dusk. By late September, days shorten but remain generous for city visits and scenic drives.

Approximate daylight table

• Early September: Sunrise 06:40–07:00 | Sunset 20:00–20:15 | Daylight ~13:00
• Mid September: Sunrise 07:05–07:15 | Sunset 19:30–19:40 | Daylight ~12:20
• Late September: Sunrise 07:35–07:45 | Sunset 19:00–19:10 | Daylight ~11:25

Sunshine, UV, and Visibility

• Sunshine: About 4–5 hours/day on average, often delivered in bright bursts between showers.
• UV index: Moderate; sunscreen and sunglasses help on clear days, especially around water and pale limestone.
• Visibility: Excellent after rain; coastal and mountain vistas can be world-class in early autumn light.

Is September a Good Time to Visit Ireland?

Many travelers consider Ireland in September the best time to visit. You’ll balance weather, value, and access to events in a way July and August often can’t match.

Pros

• Shoulder season means fewer crowds than peak summer, especially midweek and outside headline sites.
• Mild conditions suit hiking, coastal walks, and city days; not too hot, not deeply cold.
• Accommodation availability improves and prices often soften compared to July–August.
• Cultural events bloom, from theatre to food festivals, across the country.

Cons

• Changeable conditions require flexible plans and layers; showers can roll in fast on the west and north coasts.
• Sea temperatures are cool; wild swims are bracing and ferries can be weather-dependent.
• Evenings feel chilly after sunset; you’ll want a warm layer for outdoor tables.

Bottom line For travelers who want to explore, attend events, and avoid the busiest crowds, September is an ideal time. You’ll still enjoy long daylight hours, mild average temperatures, and lively evenings with locals.

Regional Weather + Travel Notes for Visiting Ireland in September

Dublin and the East: City Comfort and Culture

Weather is relatively mild with lower wet hours, perfect for urban itineraries. Spend mornings watching deer in Phoenix Park, then hop to museums that bring Irish history alive before a pub session with live music. Use Dublin as your first stop before a wider tour westward.

Kerry and Killarney National Park: Lakes, Forests, and Views

Kerry’s maritime climate keeps conditions gentle, though showers form quickly over mountains and clear just as fast. Killarney National Park shines in early autumn with calm lakes and sheltered woodland walks that feel warm under sun. Ross Castle offers lake cruises with views that pop after rain when the air turns crystal clear.

Galway City and Connemara: Atlantic Drama and Music

Expect a breezy blend of bright spells and passing rain with unforgettable light over bogs and beaches. Save indoor stops for the heaviest hours and pounce on blue-sky windows for Sky Road, the Burren, or Connemara National Park. Evenings bring a friendly buzz with visitors and locals across pubs and small venues.

Cork and the South: Food, Harbors, and the Blarney Stone

Cork’s climate is gentle in September with many ideal hours for day trips to Kinsale, Cobh, and Blarney Castle. Arrive early to kiss the Blarney Stone and miss the busiest tour groups, then walk harbor trails that gleam after showers. The city’s markets and restaurants hum without feeling too busy.

County Donegal and Northern Ireland: Rugged Coasts, Cooler Air

Donegal and Northern Ireland are cooler and windier, especially along high cliffs and wide-open beaches. The Causeway Coastal Route and Slieve League impress in early autumn light, but wind-chill can surprise, so bring a warm fleece. Clear evenings often deliver striking sunsets across north-facing bays in September.

Microclimates and Terrain: Coast, Mountains, and Inland

• Coast: Windier and slightly milder; plan extra time for exposed lookouts and bring windproof layers.
• Mountains: Rapid shifts in cloud and rain; check morning forecasts and pack a backup layer.
• Inland: Calmer winds with cool starts; expect fog at the beginning of the day that burns off by late morning.

What to Pack for Ireland in September (Checklist)

• Waterproof jacket with hood (essential on the Wild Atlantic and north coasts).
• Light, breathable base layers; a warm sweater or fleece; packable down for the chilliest mornings.
• Comfortable waterproof footwear with grip; quick-dry socks; blister plasters just in case.
• Compact, wind-resistant umbrella; daypack; reusable water bottle; small travel towel.
• Smart-casual layers for city dinners, pubs, and cultural events.
• Electronics: camera rain cover, microfiber cloth, Type G power adapter, portable battery, zip pouches.
• Optional: light gloves and a hat for early hikes; swimsuit for sheltered coves; dry bag for boat trips.

Local saying: “There’s no bad weather, only the wrong clothing.” In Ireland in September, that means layers and a reliable shell, not heavy winter wear.

September Events and Cultural Highlights (Festivals to Plan Around)

Dublin Theatre Festival (Late September into October)

This world-class festival spans stages across the city with premieres, global collaborations, and street energy. Book headliners early and note that weekend accommodation can tighten, so reserve rooms ahead.

Galway International Oyster & Seafood Festival (Late September)

Galway throws a citywide celebration of food and music that spills across pubs and public spaces. It’s a great anchor weekend for visiting Ireland with friends who love culinary events.

Culture Night (Mid–Late September; Dates Vary)

Galleries, studios, and institutions across the country open free with extended hours and pop-up performances. It’s perfect if you’re traveling on a budget and want to sample lots of neighborhoods in one night.

Note for festival seekers If parades are your priority, St Patrick’s Day (Patrick’s Day) lands in March. September swaps parade crowds for mild weather, long touring hours, and a different rhythm of cultural events.

Best Places to Visit in Ireland in September

Dublin City Highlights

• Phoenix Park: The deer rut begins in early autumn; morning light is beautiful for photography.
• Irish history: The National Museum, GPO Museum, and EPIC tell the story of the country and its people.
• Temple Bar and beyond: Find live music nightly; consider less busy neighborhoods for more local sessions.

Kerry Highlights

• Killarney National Park: Lakes and sheltered trails make for a relaxed day even if showers pass through.
• Ross Castle: Combine a visit with a Lough Leane cruise if winds are manageable.
• Drives: The Gap of Dunloe and Ring of Kerry reward early starts with fewer crowds and calm roads.

Wild Atlantic Way Classics

• Cliffs of Moher: Carry a windproof layer; visibility often turns exceptional after rain clears.
• Dingle Peninsula: Time Slea Head Drive for bright spells and low sun angles near sunset.
• Connemara: The Sky Road and boglands glow in early autumn light and change minute by minute.

County Donegal

• Slieve League: Among the best places for epic cliff views in the world; bring an extra layer.
• Glenveagh National Park: Quieter trails, castle views, and early tints of color by late September.
• Beaches: Long strands are stunning in September; mind swell and follow safety notices.

Cork and the South Coast

• Cobh: Colorful terraces and maritime stories; great after a shower when reflections pop.
• Kinsale: Coastal walks and a strong food scene; book dinner ahead on weekends.
• Blarney Castle: Arrive at opening to miss long queues and build weather flexibility into your day.

Northern Ireland Gems

• Giant’s Causeway and Causeway Coastal Route: Plan for wind and slick stones after rain.
• Carrick-a-Rede Rope Bridge: Weather-dependent; check status on the morning of your visit.
• Belfast: Museums, markets, and murals provide excellent indoor options if the forecast turns.

Sample Weather-Savvy Itineraries for a September Trip

7 Days: First-Timer Route (East to West)

• Day 1–2: Dublin (first stop) for Phoenix Park, museums, and a walking tour with pub stops.
• Day 3–4: Galway base for Connemara and the Burren; flex timing around showers to capture blue skies.
• Day 5–6: Killarney for national park walks, Ross Castle, and the Gap of Dunloe.
• Day 7: Cork and Cobh or Kilkenny; return to Dublin in the evening.

10 Days: Wild Atlantic Way Focus

• Route: Galway > Clare > Kerry > County Donegal, adding a weather buffer day in the north.
• Strategy: Use wet hours for caves, museums, and long lunches; sprint to viewpoints when fronts pass.
• Finish: Fly out of Dublin or Belfast; both connect well by road and rail.

5 Days: Culture + Theatre

• Base in Dublin for the Dublin Theatre Festival and gallery hopping.
• Day trips: Wicklow Mountains if it’s bright; Kilkenny, Newgrange, or an indoor whiskey tour if it rains.
• Evenings: Live music in intimate pubs; book a mix of iconic and off-the-beaten-path venues.

Practical Tips: Transport, Accommodation, and Costs in September

Booking in the Shoulder Season

Rates often soften compared to July and August, though event weekends can still feel busy. Book accommodation early if your dates overlap major festivals or sports fixtures, and favor free-cancellation rates to pivot with weather.

Driving and Tours

Rural roads are narrow and can be slick after rain, especially where sheep wander. If you prefer not to drive, small-group tours run frequently in September and often have fewer visitors than in summer. Build 10–20% time buffers into longer drives along the west.

Public Transport and Ferries

Intercity rail and buses connect Dublin, Cork, Galway, Belfast, and more with reliable schedules. Island ferries and rope bridges are weather-dependent; check operator notices on the morning of travel. Starting early maximizes daylight hours and avoids busier midday times.

Money-Saving Ideas

• Travel midweek for better hotel rates and fewer crowds at popular sites.
• Combine indoor and outdoor stops to make the most of every weather window.
• Look for free cultural events, city passes, and combo tickets on museums and tours.

Outdoor Safety in Early Autumn Weather

Hiking and Coastal Safety

Check Met Éireann (and the UK Met Office for Northern Ireland) forecasts each morning. Avoid cliff edges in strong winds and stick to waymarked trails that can be slick after rain. Carry a warm layer, water, and a basic first-aid kit even for short hikes.

Sea and Water Safety

Sea temperatures hover around 14–16°C in September, and cold-water shock is a real risk. Swim only where conditions are calm and lifeguards are present, and never in heavy swell or poor visibility. When in doubt, admire the view and save the dip for a pool or spa.

Gear and Comfort

A hooded waterproof jacket beats an umbrella in wind, and quick-dry layers keep you warm after a shower. Waterproof footwear with grippy soles makes the single biggest difference to comfort on trails.

Photography and Light in September

Sunrise, Sunset, and Golden Hours

As days shorten, golden hours stretch and soften, flattering landscapes and historic sites. East coasts shine at sunrise; west-facing headlands glow before sunset, especially after a clearing shower. Keep a microfiber cloth handy for your lens.

Weatherproofing Gear

Use a simple rain cover and a dry bag for cameras and phones, and avoid lens changes in drizzle. Pack a spare base layer for wind-chill on clifftops and a small towel to dry seats after rain.

Drones and Rules

Check local bylaws and national park guidance, especially around Killarney National Park and Glenveagh. Respect wildlife and never fly above crowds, farms, or livestock.

Comparing Weather in Ireland in September to Other Months

September vs August and July

July–August usually bring the warmest weather and longest evenings but also the busiest visitor numbers. September is slightly cooler with fewer crowds, often better accommodation rates, and still-long touring hours. It’s a strong balance for travelers who prefer space to explore.

September vs October

October has cooler nights, shorter daylight hours, and a higher chance of autumn storms later in the month. For hiking-friendly hours and mild averages, September is more forgiving, though early to mid-October can bring lovely color.

September vs Winter and January

Winter is colder, stormier, and darker, with January offering the fewest daylight hours. You can still explore cities and coastlines then, but routes feel very different and you’ll need heavier layers.

Considering March (St Patrick’s Day)

March brings parades and green-week festivities, but it’s cooler and changeable. If your dream is St Patrick’s Day, target March; if you want hiking, fewer crowds, and milder conditions, September is often the best time.

Ireland vs Scotland in September

Both Ireland and Scotland share a mild, maritime climate and changeable skies. West coasts in both countries are windier and wetter than the east, so packing strategy is identical: layers and waterproofs.

Facts and Data: Ireland in September by the Numbers

• National average temperature: about 10–17°C (50–63°F).
• Average rainfall: ~60–100 mm; higher along Atlantic and northern coasts.
• Daylight hours: roughly 13 hours at the beginning of the month; ~11.5 by the end.
• Sea temperature: approximately 14–16°C.
• Sunshine: 4–5 hours/day on average.

Regional snapshot (approximate)

• Dublin & East: Avg temp 11–17°C; lower rainfall; great for city walks.
• South (Cork, Kerry): Avg temp 11–17°C; moderate rainfall; sheltered parks and harbors.
• West (Galway, Clare): Avg temp 10–16°C; higher rainfall; dramatic coastal light.
• North & Northern Ireland: Avg temp 9–15°C; higher rainfall; exposed coasts feel colder.
• Midlands: Avg temp 9–16°C; moderate rainfall; calmer winds and cooler mornings.

Quick visibility of where showers are more frequent (relative)

• East: Lower
• South: Moderate
• West: Higher
• North: Higher
• Midlands: Moderate

Frequently Asked Questions about the Weather in Ireland in September

Q: What is the average temperature in Dublin in September?

A: Expect an average temperature around 11–17°C with mild afternoons and cool evenings.

Q: How much rain should I expect, and what’s the average rainfall by region?

A: Roughly 60–100 mm; the east is drier, while the west and north see more frequent showers.

Q: Do I need a waterproof jacket or umbrella?

A: Yes. A hooded waterproof jacket is essential; umbrellas struggle in wind on the west and north coasts.

Q: Are there many blue skies days, or is it mostly cloudy?

A: You’ll get frequent bright spells between showers, especially after fronts pass.

Q: What are daylight hours at the beginning and end of September?

A: About 13 daylight hours at the beginning of the month and ~11.5 by the end.

Q: Is September an ideal time to visit the Wild Atlantic Way?

A: It’s excellent—fewer crowds, dramatic light, and mild temperatures—just pack layers for wind.

Q: Can I hike without winter gear?

A: Yes, with caution. Bring layers, waterproofs, and check forecasts; mountain weather changes quickly.

Q: Is Killarney National Park good to visit in September?

A: Absolutely. It’s sheltered, scenic, and mild, with boat trips and forest walks that shine after rain.

Q: Will pubs still have live music outside peak summer?

A: Yes. Sessions run year-round in cities and many towns, especially in Galway, Dublin, and Cork.

Q: Is the Dublin Theatre Festival actually in September?

A: Yes. It typically starts in late September and runs into October.

Q: What should I pack if I’m visiting Ireland and Northern Ireland on one trip?

A: The same layered kit; the north can feel windier and cooler, so add a warm mid-layer.

Q: Are attractions like Ross Castle open regular hours?

A: Most are open on standard hours in September, with some sites shortening later in fall.

Q: Will I miss the warmest weather if I come in September?

A: The warmest weather is usually in July and August, but September stays mild and comfortable.

Q: How does Ireland’s September weather compare to other parts of the world?

A: Think Pacific Northwest in fall—mild temps, changeable skies, and bright breaks after showers.

Responsible Travel and Leave No Trace

• Stay on marked paths, respect livestock, and leave gates as found.
• Avoid muddy shortcuts after rain to limit erosion on popular routes.
• Support local pubs, guides, and family-run accommodation to keep communities thriving.

Conclusion: Why Ireland in September Is a Clever, Crowd-Light Choice

If you’re deciding when to visit, the weather in Ireland in September offers a sweet balance of mild average temperatures, manageable average rainfall, and long daylight hours. Add in cultural events like the Dublin Theatre Festival and Galway’s Oyster Festival, and you have lively evenings after active days. Pack a waterproof jacket, build a flexible route from Dublin to the Wild Atlantic Way, and you’ll explore the Emerald Isle with fewer crowds, fair prices, and frequent blue skies between showers.