Letterkenny Temperature by Month

The average annual maximum temperature in Letterkenny, Donegal County, Ireland is 13°C (55°F), with daytime highs ranging from 9°C (48°F) in January to 19°C (66°F) in July. This page covers monthly averages, day-night differences, and how Letterkenny compares to cities worldwide.

The weather in Letterkenny changes moderately throughout the year, offering enough variation to appreciate each season. Nights are cooler, with lows ranging from 12°C (54°F) to 3°C (37°F).

The chart below illustrates the average maximum day and minimum night temperatures in Letterkenny by month:

From around 4 AM to 6 AM temperatures are at their lowest; by 3 PM they've climbed to their daily peak. July, the warmest month, averages 141 hours of sunshine.

The chart below shows the average temperature throughout the year:

Letterkenny's average annual maximum temperature is 13°C (55°F). To put that in context, here's how it compares to a few well-known destinations:

Rome, Italy averages 20°C (68°F) annually, with reliably warm summers and comfortable winters.

Zermatt, Switzerland averages just 4°C (39°F) annually due to its altitude, with very cold winters and cool summers even at its warmest.

New York City, USA averages 17°C (63°F) a year, with hot humid summers and cold winters that bring regular snowfall.

Tokyo, Japan averages 21°C (70°F) a year, with hot summers, cool winters, and a well-defined cherry blossom spring.

Climate temperature data is typically calculated as a 30-year average. This smooths out year-to-year variability and gives a more reliable picture of what a place is actually like, rather than what happened in any single unusual year.

The readings come from a range of sources, land-based weather stations, ocean buoys, ships, and satellites. That data is collected by weather services around the world, then pooled, quality-checked, and averaged to produce the climate records you see here.

Global average temperatures have risen by around 1.2°C since the pre-industrial era, and the effects are visible across many regions. Winters are milder on average, with fewer frost days and less snow in many parts of the world. Heatwaves are more frequent and more intense, and Europe's summers of 2018, 2019, and 2020 all set records.

Summers are also getting drier in some areas, while winter rainfall has increased in others. This contributies to higher river levels and more flooding. In many countries, spring arrives earlier and autumn lasts longer. It has knock-on effects for wildlife, agriculture, and local ecosystems.

For more on Letterkenny's weather, including monthly rainfall, sunshine hours, and humidity, visit our Letterkenny climate page.