Weather and seasons
May and June. May is the driest month of the year at Valentia (94 mm over 13.5 wet days) and June has the fewest wet days of any month (12.8) with sunset near 22:00, which matters on a route whose two longest stages are given 8 to 10 hours. Both sit inside the operating season and neither has yet reached the midge and crowd peak of July and August.
Kerry is wet, not cold. Valentia Observatory averages a January day of 9.8 C and a July day of 18 C, and the route tops out around 372 m, so snow and cold rarely decide anything: rain and daylight do. May and June are the driest and brightest months, November to January the wettest at 180 to 190 mm over roughly 21 wet days apiece, and the walking-holiday infrastructure follows the same shape, with the two self-guided operators we checked selling the trail from 1 March and from April respectively and both finishing on 31 October. Outside that window the towns of Killarney and Kenmare carry on normally, and in the villages the split is between pubs and restaurants rather than between open and shut: the hotel bar and a restaurant at Glenbeigh and the pub at Caherdaniel all publish year-round food, while Sneem's longest-standing restaurant is described locally as running Easter through the summer and the Waterville hotel restaurant was still showing a previous year's season when we read it. Most of these villages have one or two kitchens, so a single seasonal closure takes the evening meal away rather than narrowing the choice, and an out-of-season walk needs a phone call to each stage end before you commit to the stages. Two things do not change with the month: 36 percent of the Way is on local roads, which stay walkable in anything, and the official trail description flags the stretch between Derrycunnihy Church and Lord Brandon's Cottage as flooding after heavy rainfall at various times of year.
Mild rather than cold, at an average daytime 9.8 C, so what limits the month is water and light rather than temperature. Daylight is 8.4 hours.
9.8°C high · 5.1°C low · 8.4 h (sunrise 08:37, sunset 16:57 local)Watch for: Wind on the open crossings, and water in the low ground: the official trail description flags the stretch between Derrycunnihy Church and Lord Brandon's Cottage as flooding after heavy rainfall.Rain drops well off the winter peak and light is back to ten hours, which is the first real change since November. The ground has had a full winter of it and has not started to recover.
9.9°C high · 5.1°C low · 10.0 h (sunrise 07:50, sunset 17:53 local)Watch for: Gales are still frequent and the exposed sections give no shelter to sit out a squall.The first month that works if you accept wet ground: 11.9 hours of light, rainfall down to around 116 mm, and one of the two self-guided operators we checked selling the trail from 1 March.
10.8°C high · 5.5°C low · 11.9 h (sunrise 06:50, sunset 18:43 local)Watch for: Ticks. The Health Protection Surveillance Centre puts Irish tick activity from spring to autumn, and much of this route is exactly the long grass, heath and woodland edge they favour.Both self-guided operators we checked are running by April, daylight is up to 14 hours, and at 108 mm this is one of the drier months. Midges have not started.
12.4°C high · 6.7°C low · 14.0 h (sunrise 06:38, sunset 20:37 local, clocks go forward in late March)Watch for: Ticks in long grass and bracken. In a dry spring spell the national park posts fire-danger notices, and fires of any kind are prohibited in the park at all times.The driest month at Valentia, 94 mm over 13.5 wet days, with nearly 16 hours of light and the full season running. Midges are barely started.
14.5°C high · 8.8°C low · 15.8 h (sunrise 05:41, sunset 21:27 local)Watch for: Ticks are active. Midges start to appear in the sheltered inland valleys towards the end of the month.The longest light of the year, sunset near 22:00, and the fewest wet days of any month at 12.8. That combination is what turns the 30 km stages from a race into a long day.
16.6°C high · 11.1°C low · 16.8 h (sunrise 05:14, sunset 22:02 local)Watch for: Midges. The highland midge is active from late spring and bites hardest in still, humid air, so the sheltered inland valleys are worse than the windy coastal sections.Rain climbs back to 117 mm over 16 wet days, more than April, May or June, and peak midges arrive with peak crowds. Nothing is wrong with July, it is simply the least favourable of the summer months here.
17.8°C high · 12.9°C low · 16.3 h (sunrise 05:33, sunset 21:54 local)Watch for: Midges at their worst, particularly in the evening and in the sheltered valleys. Ticks are still active.As July for weather and crowds. What is different is the start of the red deer rut in Killarney National Park, which the first and last stages run through.
18°C high · 12.8°C low · 14.7 h (sunrise 06:20, sunset 21:04 local)Watch for: Midges. The red deer rut begins in the national park, and the park service asks visitors to keep their distance from rutting stags.The crowds go and the trail is still fully served. The cost is rain climbing to 130 mm and daylight down to 12.7 hours, which still covers the two longest stages.
16.9°C high · 11.7°C low · 12.7 h (sunrise 07:11, sunset 19:55 local)Watch for: The deer rut is at its loudest in the national park. Midges fade through the month.The last month of the walking season, and the weather knows it: 173 mm over 18 wet days. Mornings are dark until about 08:00 local, because Kerry sits at the western edge of the time zone, and the clocks go back late in the month.
14.4°C high · 9.5°C low · 10.8 h (sunrise 08:01, sunset 18:46 local before the clocks go back in late October)Watch for: Autumn gales on the exposed crossings. The deer rut runs into this month.The wettest month at Valentia, 189 mm across 21 wet days, and light down to 8.9 hours.
11.8°C high · 7.2°C low · 8.9 h (sunrise 07:56, sunset 16:48 local)Watch for: Atlantic gales on the exposed crossings.The shortest light of the year at 7.8 hours, sunrise 08:37 and sunset 16:28.
10.4°C high · 5.8°C low · 7.8 h (sunrise 08:37, sunset 16:28 local)Watch for: Light, above everything else. Frost is occasional and lying snow rare at these heights (the route tops out around 372 m), so the limits here are darkness and water rather than winter mountain conditions.