Weather in Shannon in September 2025
Average weather
Average temperature in Shannon in September
Going from a maximum of +81°F during the day to a minimum of +41°F during the night, the temperature in September averages around +64°F.
The average maximum temperature goes down 5% by the end of the month, compared with the beginning of the month, from +66°F to +64°F.
Is Shannon warm or cold in September?
Shannon is typically mild in September.
Maximum temperatures go down compared to the previous month from +64°F to +63°F. The minimum temperature also goes down from +54°F to +50°F.
Pack a light jacket as it will be warm in the day and cool in the evenings.
September is one of the warmest months in Shannon, here is the comparison with other months:
Climate in Shannon in September
| August | September | October | ||||
|---|---|---|---|---|---|---|
| Avg. temperature | ||||||
| +64°F | +63°F | +55°F | ||||
| Min. temperature | ||||||
| +39°F | +34°F | +27°F | ||||
| Max. temperature | ||||||
| +82°F | +81°F | +70°F | ||||
| Rainfall | ||||||
| 91 mm | 80 mm | 102 mm | ||||
| Wind | ||||||
| 3 m/s | 3 m/s | 4 m/s | ||||
| Humidity | ||||||
| 84% | 85% | 87% | ||||
| Air pressure | ||||||
| 1014 HPa | 1014 HPa | 1010 HPa | ||||
| Sunny days | ||||||
| 1 | 1 | 1 | ||||
| Cloudy days | ||||||
| 9 | 10 | 10 | ||||
| Rainy days | ||||||
| 22 | 19 | 20 | ||||
| Snowy days | ||||||
| 0 | 0 | 0 | ||||
September weather is still as ok as in August. It’s getting colder in September. From +64°F in the day, the average maximum temperature lowers to +63°F. As September arrives, the amount of rainfall goes down. On average, the rainfall volume decreases from 91 mm to 80 mm. Humidity rises from 84% to 85%. The average wind speed doesn’t change much during September, staying around 3 m/s. The amount of sunny days stay about the same, averaging 1 sunny days during the month.
October brings much the same weather, it remains ok.
Wind
The average wind speed is 4 m/s getting up to 9 m/s which is a medium breeze. You can feel it, especially getting out of the water.
The average wind speed in Shannon is gradually increasing during September, going from 1 m/s to 4 m/s over the course of the month.
Rain
How was the weather last September in Shannon?
Climate Change Over the Years
The climate in Shannon in September has not changed that much over the last 43 years.
The average temperature was the lowest in 1979 (+53°F) and the highest in 2023 (+57°F). The driest year was 2001 with only 746 mm of rainfall, and the wettest year was 2009 with 1263 mm.
FAQ
Is September a good time to visit Shannon?
Can you sunbathe in Shannon in September?
Is Shannon rainy in September?
Is it sunny in Shannon in September?
Other cities in Ireland
Monthly weather in Shannon
Source of the data
For this page, we’ve looked at the typical weather in Shannon, based on historical hourly weather data from January 1, 1979, to December 31, 2023.
For past dates, we show actual recorded data at the location at that time. Forecasts are based on recorded weather during that day of the year, averaged over the total years for which we have records (unless stated otherwise). The daily temperature is the highest recorded temperature in the shadow during that day.