Greencastle has some of the coolest summers among Irish towns
The coldest hours of a January night bottom out at 2.9°C on average. By rainfall alone, it ranks wetter than 86% of Irish towns. Decade by decade the climate has edged up, 0.3°C above 1981–2010. Plan time outside for July and August, when highs sit at 18°C.
Met Éireann 1991–2020 averages for the town’s own square kilometre.
A year in Greencastle at a glance
Each month’s typical high and low, in °C.
What stands out about Greencastle’s climate
Compared with Irish towns, with its place among towns of 2,500+ in County Donegal beside it.
What a year in Greencastle feels like
Typical highs and lows by season and by month, from Met Éireann’s 1991–2020 averages.
About 6 air frosts a year
Ground frosts, when the grass drops below 0°C, come on about 29 nights a year. Air frosts come mostly from December to March, most of all in January (about 2).
Air frosts by month
Average nights below 0°C
Ground frosts by month
Average nights with the grass below 0°C
Counted from Malin Head’s daily readings, 1991–2020, 29 km north-west of Greencastle: Met Éireann publishes these for its stations only. At that distance, read them as the area’s climate.
About 1,206 mm of rain a year
December is the wettest month and May the driest. 7th wettest of 7 towns of 2,500+ in County Donegal. The wettest month brings about 1.9 times the rain of the driest. Malin Head records 1 mm or more on about 192 days a year, and 10 mm on about 30.
Rain by month
Millimetres
Sunshine by month
Hours, at Malin Head
Heating a home in Greencastle
81% of a year’s heating need falls between October and April. Months averaging under 10°C: November to April.
Degree days add up how far each day’s mean temperature falls below 15.5°C over a year.
Living with Greencastle’s climate
What the averages mean for a garden, a free afternoon and a bad-weather day.
In half of years the last air frost at Malin Head comes by 3 March and the first by 20 December: about 292 frost-free days in between.
Highs of 17–27°C with lows of 8°C or more: Jul and Aug.
Parks & trails →Averages smooth over storms, floods and heatwaves; Greencastle’s hazards page covers the risks.
Flood & hazards →Met Éireann’s nearest station: Malin Head
Malin Head is 29 km north-west of Greencastle, the nearest of the 25 synoptic stations where Met Éireann records the weather around the clock. The station stands 20 m above sea level; Greencastle’s centre, 68 m.
| Month | High | Low | Rain | Air frosts | Sun (hours) |
|---|---|---|---|---|---|
| January | 8.2°C | 3.9°C | 119 mm | 1.8 | 41 |
| February | 8.4°C | 3.8°C | 95 mm | 1.5 | 74 |
| March | 9.4°C | 4.4°C | 81 mm | 1.1 | 121 |
| April | 11.1°C | 5.8°C | 64 mm | 0.2 | 169 |
| May | 13.2°C | 7.8°C | 65 mm | 0.0 | 216 |
| June | 15.2°C | 10.2°C | 74 mm | 0.0 | 166 |
| July | 16.9°C | 11.9°C | 86 mm | 0.0 | 147 |
| August | 17.1°C | 12.1°C | 98 mm | 0.0 | 142 |
| September | 15.8°C | 10.8°C | 95 mm | 0.0 | 112 |
| October | 13.2°C | 8.6°C | 110 mm | 0.0 | 83 |
| November | 10.5°C | 6.2°C | 122 mm | 0.3 | 45 |
| December | 8.8°C | 4.4°C | 131 mm | 1.3 | 35 |
| Year | 12.3°C | 7.5°C | 1,138 mm | 6 | 1,348 |
The table is Malin Head’s own record, averaged over 1991–2020 from its daily readings (ours, not a Met Éireann table). The temperatures and rain elsewhere on this page are Met Éireann’s 1 km grid at Greencastle itself; the frosts, sunshine and degree days are this station’s.
How Greencastle compares
Against the 321 Irish towns and city neighbourhoods of 2,500 or more, each read from Met Éireann’s grid at its own centre, and its place among towns of 2,500+ in County Donegal.
Warmer than it used to be
Greencastle’s 1991–2020 average is 0.3°C warmer than 1981–2010’s. The biggest change is in February (+0.4°C).
A year’s rain is 1,206 mm, up 2% from 1,179 mm.
Change by month
The two periods share 1991–2010, so the gap is a decade’s step, not the change between two separate 30-year periods.
Greencastle and its neighbours
Every town next door is within half a degree of Greencastle in January and July. Choose a measure to recolour the map; tap a town for its climate.
The towns next door, side by side
The nearest towns of 1,000+ within 19 km: a hill, a valley or the sea can make a real difference over a short distance.
| Town | July high | January low | Rain a year |
|---|---|---|---|
| Greencastle | 17.9°C | 2.9°C | 1,206 mm |
| Moville 3.1 km | 18.0°C about the same | 2.8°C about the same | 1,292 mm |
| Carndonagh 18 km | 17.6°C about the same | 3.0°C about the same | 1,351 mm |
Each town’s colour is Met Éireann’s 1 km grid at its own centre, so towns a few kilometres apart can differ.
Greencastle weather by month
Average daily high and low, mean temperature and rain, 1991–2020, for the town itself (Met Éireann’s 1 km grid).
| Month | High | Low | Mean | Rain |
|---|---|---|---|---|
| January | 7.6°C | 2.9°C | 5.2°C | 123 mm |
| February | 8.0°C | 2.8°C | 5.4°C | 99 mm |
| March | 9.5°C | 3.6°C | 6.5°C | 94 mm |
| April | 11.7°C | 5.1°C | 8.4°C | 71 mm |
| May | 14.4°C | 7.3°C | 10.8°C | 69 mm |
| June | 16.5°C | 9.8°C | 13.1°C | 82 mm |
| July | 17.9°C | 11.6°C | 14.8°C | 95 mm |
| August | 17.9°C | 11.7°C | 14.8°C | 110 mm |
| September | 16.2°C | 10.2°C | 13.2°C | 88 mm |
| October | 13.1°C | 7.8°C | 10.4°C | 118 mm |
| November | 10.1°C | 5.2°C | 7.6°C | 123 mm |
| December | 8.1°C | 3.3°C | 5.7°C | 134 mm |
| Year | 12.6°C | 6.8°C | 9.7°C | 1,206 mm |
How much a month can swing
March swings the most: over 30 years its average ranged from 4.1°C (2013) to 9.2°C (2012). June is the most reliable, staying within 2.9°C.
Where Greencastle’s numbers come from
Averages over 30 years, not a forecast: the town’s own from Met Éireann’s grid, the frosts, sunshine and degree days from its nearest station.
- Temperature and rain: Met Éireann’s 1991–2020 averages on its 1 km grid (Climatological Notes 22 and 23), read at the grid point nearest Greencastle’s population centre (0.4 km away).
- Weather station: the nearest of Met Éireann’s 25 synoptic stations, Malin Head, 29 km north-west, from Met Éireann’s station list.
- Frosts, sunshine, degree days: Malin Head’s daily readings from Met Éireann (clidata.met.ie), 1991–2020, averaged by month: a month counts when 27 or more of its days were read (rain and sunshine: every day), and a figure needs 10 such years.
- Then and now: Met Éireann’s 1981–2010 averages on the same 1 km grid, at the same point.
- Altitudes: the town’s ground from the Copernicus GLO-30 surface model (a few metres high in built-up places), the station’s from Met Éireann.
- Comparisons: every Irish town and city neighbourhood of 2,500 or more, read the same way; the five city totals are left out.
- Not on this page: snow and wind. Met Éireann publishes neither on a grid; the frosts and sunshine here are its nearest station’s, not the town’s own.
Met Éireann 30-year averages · Met Éireann open data. Under Creative Commons Attribution 4.0 (CC BY 4.0).
Questions about Greencastle’s climate
How warm does Greencastle get in summer?
The warmest month is July, when afternoons average 17.9°C.
How cold does Greencastle get in winter?
February nights average 2.8°C, the coldest of the year. At Malin Head, the nearest Met Éireann station, the air drops below 0°C on about 6 nights a year (1991–2020).
How much rain does Greencastle get?
About 1,206 mm a year, more than 86% of Irish towns. December is the wettest month (134 mm) and May the driest (69 mm).
How sunny is it?
Malin Head, 29 km north-west, averages about 1,348 hours of sunshine a year (1991–2020, from its daily record). Met Éireann publishes no sunshine figure for the town itself.
Are these figures for Greencastle itself?
Partly. The temperatures and rain are Met Éireann’s 1991–2020 averages on its 1 km grid, read at Greencastle’s population centre; the frosts, degree days and year-to-year swings are those of Malin Head, 29 km north-west, the nearest of its synoptic stations.
Where do these figures come from?
Met Éireann’s 1991–2020 climate averages, published as maps of Ireland in 1 km squares (Climatological Notes 22 and 23); the page reads the square at Greencastle’s population centre. They are 30-year averages, not a forecast.
Copyright Met Éireann. Source: www.met.ie. This data is published under a Creative Commons Attribution 4.0 International (CC BY 4.0) licence. Met Éireann does not accept any liability whatsoever for any error or omission in the data, their availability, or for any loss or damage arising from their use. This material has been modified from the original: TownRatings reads the 1 km grid at each town’s population centre. Today’s forecast for Greencastle →
Contains Central Statistics Office (CSO) data, Census 2022, and Tailte Éireann boundaries (CSO Urban Areas, Small Areas, local electoral areas, constituencies), under Creative Commons Attribution 4.0 (CC BY 4.0).