Weather in Galway in September

Shoulder season. September is shoulder season in Galway — cheaper, quieter, and a genuine gamble. You should expect rain on 16 days of the month, which is more days wet than dry.

September ranks 3 of 12 in Galway. Only June scores clearly higher, and the difference is small enough to be settled by price rather than weather.

This is persistent light rain rather than storms: 16 wet days but only 2 heavy ones. It rarely cancels anything outright, and it rarely fully clears either. A jacket beats an umbrella. Pack for 17.3 °C days and 10 °C nights; the spread matters more here than any single number.

What the averages hide

The averages here are honest — no hidden extremes worth planning around. Across the twenty years measured, the hottest September day reached 24.1 °C and the coldest night fell to 2.2 °C, and the wettest single day dropped 44 mm — roughly 51% of the month's rain in one day.

September is statistically steady but not small: the year-to-year variation is modest in relative terms, yet the wettest September on record still delivered 163 mm against 22 mm in the driest. In a month this wet, even a tame spread is a lot of rain in absolute terms — the 86 mm average is a reasonable planning figure, not a promise.

Wind is light at 12.3 km/h, so the temperature on the page is close to the temperature on your skin, and humidity runs at 86%, high enough to notice on the warm days without dominating them.

How September sits in the year

The month is on the way down: 1.8 °C cooler than August, with October dropping another 3.7 °C. The first week and the last are not the same trip.

Daylight in September

12.8 hours of daylight, losing 2.1 hours across the month. That is between Galway's extremes of 16.9 and 7.6 hours, so days are long enough not to constrain the plan.

An inland climate

Despite being inland, the year stays fairly even: 17.1 °C between the year's warmest afternoons and coldest nights.

How busy it gets

Peak season. Expect the highest prices of the year and to be booking well ahead. If the dates are flexible, April is the trade worth considering — 14 points weaker on weather, and materially quieter.

Crowd levels are estimated from climate desirability and school-holiday calendars, not from visitor numbers.

September in Galway versus nearby

If Galway is one option among several, the nearby comparison is worth making. Cork is close enough to be a coin toss — within a degree on temperature, 1 day less rain. Dublin is close enough to be a coin toss — within a degree on temperature, 3 days less rain.

So: September is effectively as good as it gets here — 3 points behind June, which is inside the margin where the weather stops being the deciding factor and price starts being it.

Every month in Galway

See all twelve months in Galway, or where else to go in September.