Summers in Castlerea are cooler than in 94% of Irish towns
Deep winter brings January lows near 2.1°C. Winter and summer sit 17°C apart. By rainfall alone, it ranks wetter than 85% of Irish towns. The heating season runs November to April: each of those months averages under 10°C.
Met Éireann 1991–2020 averages for the town’s own square kilometre.
A year in Castlerea at a glance
Each month’s typical high and low, in °C.
What stands out about Castlerea’s climate
Compared with Irish towns, with its place among towns of 2,500+ in County Roscommon beside it.
What a year in Castlerea feels like
Typical highs and lows by season and by month, from Met Éireann’s 1991–2020 averages.
About 29 air frosts a year
Ground frosts, when the grass drops below 0°C, come on about 70 nights a year. Air frosts come mostly from November to April, most of all in January (about 8).
Air frosts by month
Average nights below 0°C
Ground frosts by month
Average nights with the grass below 0°C
Counted from Knock Airport’s daily readings, 1996–2020, 27 km north-west of Castlerea: Met Éireann publishes these for its stations only. At that distance, read them as the area’s climate.
About 1,198 mm of rain a year
December is the wettest month and April the driest. 2nd wettest of 3 towns of 2,500+ in County Roscommon. The wettest month brings about 1.7 times the rain of the driest. Knock Airport records 1 mm or more on about 209 days a year, and 10 mm on about 42.
Rain by month
Millimetres
Sunshine by month
Hours, at Knock Airport
Heating a home in Castlerea
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 Castlerea’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 Knock Airport comes by 6 April and the first by 26 November: about 234 frost-free days in between.
Highs of 17–27°C with lows of 8°C or more: Jun, Jul and Aug.
Parks & trails →Averages smooth over storms, floods and heatwaves; Castlerea’s hazards page covers the risks.
Flood & hazards →Met Éireann’s nearest station: Knock Airport
Knock Airport is 27 km north-west of Castlerea, the nearest of the 25 synoptic stations where Met Éireann records the weather around the clock. The station stands 201 m above sea level; Castlerea’s centre, 69 m.
| Month | High | Low | Rain | Air frosts | Sun (hours) |
|---|---|---|---|---|---|
| January | 6.7°C | 2.0°C | 135 mm | 7.7 | 48 |
| February | 7.3°C | 1.9°C | 113 mm | 6.9 | 62 |
| March | 9.0°C | 2.6°C | 97 mm | 5.0 | 102 |
| April | 11.5°C | 4.1°C | 79 mm | 1.8 | 147 |
| May | 14.2°C | 6.5°C | 93 mm | 0.0 | 174 |
| June | 16.2°C | 8.9°C | 96 mm | 0.0 | 145 |
| July | 17.3°C | 10.5°C | 109 mm | 0.0 | 121 |
| August | 17.1°C | 10.6°C | 118 mm | 0.0 | 120 |
| September | 15.4°C | 9.1°C | 110 mm | 0.0 | 101 |
| October | 12.2°C | 6.4°C | 129 mm | 0.1 | 85 |
| November | 8.9°C | 3.9°C | 144 mm | 1.6 | 55 |
| December | 7.0°C | 2.3°C | 152 mm | 6.0 | 39 |
| Year | 11.9°C | 5.7°C | 1,372 mm | 29 | 1,199 |
The table is Knock Airport’s own record, averaged over 1996–2020 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 Castlerea itself; the frosts, sunshine and degree days are this station’s.
How Castlerea 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 Roscommon.
Warmer than it used to be
Castlerea’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 1,198 mm, up 3% from 1,164 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.
Castlerea and its neighbours
Every town next door is within half a degree of Castlerea 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 |
|---|---|---|---|
| Castlerea | 19.1°C | 2.1°C | 1,198 mm |
| Ballaghaderreen 16 km | 18.8°C about the same | 2.0°C about the same | 1,285 mm |
| Ballyhaunis 19 km | 18.8°C about the same | 2.0°C about the same | 1,284 mm |
Each town’s colour is Met Éireann’s 1 km grid at its own centre, so towns a few kilometres apart can differ.
Castlerea 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 | 7.9°C | 2.1°C | 5.0°C | 124 mm |
| February | 8.6°C | 2.0°C | 5.3°C | 98 mm |
| March | 10.3°C | 2.9°C | 6.6°C | 92 mm |
| April | 13.0°C | 4.3°C | 8.7°C | 77 mm |
| May | 15.7°C | 6.7°C | 11.2°C | 78 mm |
| June | 18.0°C | 9.4°C | 13.7°C | 83 mm |
| July | 19.1°C | 11.2°C | 15.2°C | 87 mm |
| August | 18.8°C | 11.1°C | 14.9°C | 97 mm |
| September | 16.9°C | 9.1°C | 13.0°C | 85 mm |
| October | 13.5°C | 6.5°C | 10.0°C | 117 mm |
| November | 10.2°C | 4.0°C | 7.1°C | 127 mm |
| December | 8.1°C | 2.3°C | 5.2°C | 133 mm |
| Year | 13.3°C | 6.0°C | 9.7°C | 1,198 mm |
How much a month can swing
December swings the most: over 25 years its average ranged from 0.6°C (2010) to 6.5°C (2018). September is the most reliable, staying within 2.7°C.
Where Castlerea’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 Castlerea’s population centre (0.4 km away).
- Weather station: the nearest of Met Éireann’s 25 synoptic stations, Knock Airport, 27 km north-west, from Met Éireann’s station list.
- Frosts, sunshine, degree days: Knock Airport’s daily readings from Met Éireann (clidata.met.ie), 1996–2020, 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 Castlerea’s climate
How warm does Castlerea get in summer?
July is the warmest month, with average highs of 19.1°C.
How cold does Castlerea get in winter?
The coldest nights come in February, averaging 2.0°C. At Knock Airport, the nearest Met Éireann station, the air drops below 0°C on about 29 nights a year (1996–2020).
How much rain does Castlerea get?
About 1,198 mm a year, more than 85% of Irish towns. December is the wettest month (133 mm) and April the driest (77 mm).
How sunny is it?
Knock Airport, 27 km north-west, averages about 1,199 hours of sunshine a year (1996–2020, from its daily record). Met Éireann publishes no sunshine figure for the town itself.
Are these figures for Castlerea itself?
Partly. The temperatures and rain are Met Éireann’s 1991–2020 averages on its 1 km grid, read at Castlerea’s population centre; the frosts, degree days and year-to-year swings are those of Knock Airport, 27 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 Castlerea’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 Castlerea →
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).