Climate Insights for Letterkenny

The climate in Letterkenny is cool. The average annual temperature is 10°C and approximately 1481mm of precipitation falls per year. Letterkenny receives a notable amount of rainfall throughout the year, including during its driest month. Letterkenny is in the Northern Hemisphere. Summer begins at the end of June and lasts through September. The summer months are: August, July, June. The coldest months are February, March, January, when temperatures can drop to 4°C. Light snow can occur between January and December.

Letterkenny sees moderate temperature variation throughout the year, ranging from 4°C to 16°C. August is the warmest month, though highs remain moderate at 16°C with a mean of 15°C. February is the coolest month, with minimum temperatures around 4°C and an average of 6°C. Daily temperature variation is modest, with an average difference of 4°C between highs and lows. The sharpest temperature change occurs between April and May, with a 3°C shift in average temperatures.

Letterkenny is a fairly wet location, receiving approximately 1481mm of precipitation annually, which averages out to around 123mm per month. The wettest month is August, averaging 160mm of rainfall. December and January also tend to see above-average precipitation. The driest month is April, with just 68mm. That's 92mm less than August, the wettest month. Rainfall is relatively evenly distributed throughout the year, so there is no pronounced dry or wet season to plan around. Light snowfall can occur between January and December, totalling around 17cm annually. February is the snowiest month with approximately 7cm.

Letterkenny is relatively calm, with an average annual wind speed of 6km/h. For context, sustained winds below 12km/h are generally light, while anything above 25km/h is considered strong. The windiest month is February, averaging 7km/h, though still comfortable for most outdoor activities. The calmest conditions occur in May, with average winds dropping to 5km/h, making it an ideal period for wind-sensitive activities. There is moderate seasonal variation in wind speed, with a 2km/h gap between the calmest and windiest months. Wind tends to be stronger during winter months, driven by seasonal pressure systems. The seasonal averages break down to 7km/h in winter, 6km/h in spring, 5km/h in summer, 6km/h in autumn.

It is currently summer in Letterkenny, which began on June 21, 2026. Letterkenny is in the Northern Hemisphere, where spring begins in March, summer in June, autumn in September, and winter in December. The warmest period peaks in August at around 16°C, while the coldest stretch bottoms out in February near 4°C. Autumn is next, beginning on September 23, 2026 — 93 days from now.

The table below shows monthly climate averages for Letterkenny based on historical weather data. Min and max temperatures represent typical overnight lows and afternoon highs for each month, shown in degrees Celsius (°C). Precipitation is measured in millimetres (mm) and indicates the average total rainfall per month. Snow is measured in centimetres (cm) and reflects average monthly snowfall accumulation. Wind speed is the average sustained speed in kilometres per hour (km/h). All values are based on averages from over 10 years of historical weather data. The current month is highlighted for quick reference.