A continuation of and occasional improvement on the weather of the summer high season, overall September could offer the perfect vacation in Ireland with a bit of luck. Air temperatures and water temperatures are still some of the year's best (just with a refreshing fall crispness in the air), and yet crowds are way down on August because kids are back at school and families are not on holidays now.

Weather

September, when the summer weather departs and when fall officially arrives, can still bring some of the best weather of the year to Ireland. Air temperatures remain high (and actually only just below July and August's peak temperatures) while rainfall is not significantly up from any of the summer months. 

Killarney & Southwestern Ireland

Change is in the air, but in Southwestern Ireland, it's not really here yet. Weather is more summery than it is autumnal, with average daily highs of 62.6°F/17°C only just below the July-August level, and average monthly rainfall only slightly up on these months. In the water, it is still very warm (for Ireland, at least!) after having been heated over the summer (60.8°F/16°C).

Dublin & Eastern Ireland

September sees rainfall down to just 2.36 inches/ 60mm for the month, one of the lowest of any period of the year, and average monthly temperatures stay in a range of 50-62.6°F/10-17°C, meaning you might be able to count on decent walking weather just as much now as in the summer high season. There are less daily sunshine hours on average (4) than there have been at any time since March, however. 

Belfast & Northern Ireland

Four daily hours of sunshine but rainfall (3.14 inches/ 80mm) that is approaching some of its highest levels of the year in Belfast makes this region an unpredictable place weather-wise in September. You might get gorgeous summery weather, you might get something much colder and bleaker. Seawater temperatures remain at their annual high (57.2°F/14°C) however.

Crowds & Costs

You will soon see that, if the weather holds, this is a good time to come to Ireland. With school holidays over and far less people traveling around the country, key accommodations and attractions are no longer at peak capacity and will more than likely offer lower rates. This is shoulder season, so costs are not yet at their winter lows. 

Where to Go

Killarney & Southwestern Ireland

Ireland's fairly dry, clement September weather makes it appealing to spend time outdoors: all too soon, proper winter will be descending and places will either close up or become less appealing to visit. The far southwest is a good place to start.

In Co. Kerry there is fabulous mountain and coastal hiking on its legendary southwest peninsulas, such as the Kerry Way (Iveragh Peninsula) and Dingle Way (Dingle Peninsula). You could also try some walking closer to civilisation just in case the rains do come. Near Killarney, try spending time in Killarney National Park, Ireland's oldest national park. Alongside the walks, bad weather attractions include splendid stately home Muckross House & Gardens in the middle of the park and the ruin of Ross Castle.

Or make a visit to one of Ireland's most important ancient sites, the Rock of Cashel: a fortress and one-time seat of power of Irish royalty, with medieval ruins and beautiful riverside and woodland walks. Or visit one of the islands positioned invitingly off the mainland coast.

Take a boat trip across to the rocky Skellig Islands near Dingle or, better yet, travel to the otherworldly and traditional Aran Islands near Galway. Soon boat trips here will dwindle as rougher seas and less visitors mean fewer crossings as of next month.

See here for a road trip from Dublin via the Rock of Cashel to Ireland's west coast.

Dublin & Eastern Ireland

Make the most of some of the last fair weather of the year and enjoy the countryside for activities this month. The Wicklow Way boasts some of the most delightful hiking in the whole region and a top drawer selection of the very best things to do. Think chocolate box villages like Enniskerry, crashing waterfalls like Powerscourt Waterfall on the enchanting Powerscourt Estate, wooded hills and monastic ruins like Glendalough Abbey.

Gorgeous sandy beaches line the eastern coastline; some, like Loughshinney, are located within Co. Dublin and are within an easy drive of the city while others, like the divine Rosslare Strand, are in sight of where the ferry from Wales arrives. Should the wilder weather come, factor in some days in Dublin which is enlivened by the Dublin Fringe Festival this month. 

Belfast & Northern Ireland

Exploring this region's phenomenal nature while any lingering fair weather still gives you the opportunity this month. The essential trip is to the Causeway Coast, where the Unesco-listed Giant's Causeway, a swathe of thousands of interconnecting basalt columns, makes for one of the most spectacular coastal attractions you could ever hope to see. Ideally at this time of year you would get a mix of sun and wind, which gives the place a wild, ethereal feel.

For a longer hike, there is nothing more epic than the Ulster Way, a 625-mile loop passing through almost all of Northern Ireland and one of the UK's longest and loveliest hiking routes. Try the Lough Bradan-Gortin or the Gortin-Moneyneany sections for some of the best vistas of the whole walk, and stretches that go through Northern Ireland's biggest mountains, the Sperrin Mountains.

If you want a walk that is more sheltered and closer to civilisation, the red squirrel and sculpture trail beginning at Glenarm Castle is exquisite at this time of year. And stop in Belfast, which celebrates its annual international tattoo, an extravaganza of parades, live music and dance, this month. See here for an itinerary taking in Belfast and Northern Ireland, as well as Dublin.

What to Do

Killarney & Southwestern Ireland

If the weather holds, and hold it well might as September regularly outdoes August for fine weather, then spend time outdoors this month. With water temperatures at their highest of the year, and now with the crowds gone, going to the beach could be best around now. Swimming at some of the country's very best sandy beaches lacing the southwestern peninsulas is a wonderful activity, especially while sea water temperatures remain relatively high: try Keem Bay on Achill Island, Co, Mayo or Coumeenole Beach near Dunquin in Co. Kerry.

Then there is the hiking, with jaw-dropping trails threading around the Iveragh Peninsula (on the Kerry Way) or Dingle Peninsula (on the Dingle Way). Cycling is just as enjoyable as hiking, and you can take in much of the best of this west coastline on the Wild Atlantic Way, with this itinerary focusing on the snaking peninsulas, craggy islands and colorful coastal villages of Co. Mayo.

Or take advantage of warm waters to try some sea kayaking, with Donegal region widely regarded as one of the best places for this activity in the world, or diving, with Killary Harbour in Connemara, Co.Galway, a brilliant place to do it along with several locations in Co. Cork. 

Dublin & Eastern Ireland

Make the most of any lingering fine weather and try some of the region's sensational hiking as a priority this month. The Wicklow Way showcases the very finest aspects of Eastern Ireland, and kicks off from Dublin's southerly suburbs. Or try a leisurely wander and swim on some of the region's stunning sandy beaches, lacing all of the eastern coast and never better than in the sunny summer weather and warmer summer water temperatures.

Remember that this region is also known as 'Ireland's Ancient East'. So for a great insight into Ireland's prodigious history with outdoor and indoor activities on offer, visit the Irish National Heritage Park near Wicklow, walking you through 9000 years of the country's past in a magical open-air setting.

Quality diving is also on offer at the Muglins by Dalky Island near Dublin: a rock covered in seabirds most of the year with some of Ireland's greatest scuba diving beneath. There are numerous delightful wild swimming places along the coastline, to be relished while sea water temperatures remain relatively high.

Belfast & Northern Ireland

There will not be that much more fine weather in the year once this month is out, so enjoy the outdoors to the full while you can. Hiking along some of the craggy Causeway Coast, including the stupendous stacks of basalt columns that make up the Unesco-listed Giant's Causeway, will likely be this region's most popular activity.

But the hike that reveals this region's fantastic scenery better than any other is the 625-mile Ulster Way, taking the walker to high mountains, wild forests and lonely lakes as well as the breathtaking coastline. See above for the best sections of the Ulster Way to hike. Or spot locations from blockbuster TV series Game of Thrones, with many filming locations scattered through this region.

Sights to check out in summer include the Downhill Strand in Co. Derry, Tollymore Forest Park, in Co. Down and Co. Antrim's famous Dark Hedges, an avenue of mysterious ancient beech trees now tinged with fall colors and one of Ireland's most photographed natural attractions. The seas are warm and quite calm and good for sea kayaking this month, and in this regard Northern Ireland leads the way with its stunning North Coast Sea Kayak Trail between Co. Londonderry and Co. Antrim, passing the Giant's Causeway. 

September Events

Belfast International Tattoo Extravaganza of military and community themed dance, parades and music in early September in Belfast.

Dublin Fringe Festival Held over two weeks at the start of September in Dublin, this event, of the same ilk as other fringe festivals, focuses on emerging talent in the field of dance, theater, music, visual arts and the like. Performing artists also run workshops over the festival to pass on some of their skills to others. 

International Oyster & Seafood Festival Galway on the west coast of Ireland has access to some incredible seafood which is showcased at this standout food festival over three days towards the end of the month.

Traveling in Ireland in September? Check out these great itineraries.

Dublin City & Wicklow Way Walk (6 Days).  Combine Ireland's energetic capital city with a few days walking in Wicklow National Park on this 6-day itinerary, ideal for those who want to experience both the city and countryside. You'll start with two nights in the city taking in its historical tours, followed by four nights traversing the mountain passes and glacial valleys of the Wicklow Way through expansive views and cozy villages.

Self-Guided Ring of Kerry Bike (8 Days). Cycle the historic Ring of Kerry on this 8-day biking tour, staying at night in cozy B&Bs. Trace the coastline of the Iveragh Peninsula, explore Killarney National Park, and visit the historic villages of Sneem and Kenmare. See 6th-century ruins on Skellig and Valentia Islands, and enjoy sweeping views of the wild Atlantic Ocean. You'll cycle along quiet country roads, take in the serene countryside, and hear local stories and legends in the neighborhood pub.

More Helpful Information

Ireland in August
Ireland in October
Best Time to Visit Ireland
Getting Around Ireland