Newcastle has milder winter nights than 88% of Irish towns
High summer brings afternoon highs near 19.8°C. October has warmed most since 1981–2010, part of a 0.2°C rise. Central heating does most of its work from November to April, in months below 10°C on average.
Met Éireann 1991–2020 averages for the town’s own square kilometre.
A year in Newcastle at a glance
Each month’s typical high and low, in °C.
What stands out about Newcastle’s climate
Compared with Irish towns, with its place among towns of 2,500+ in County Wicklow beside it.
What a year in Newcastle feels like
Typical highs and lows by season and by month, from Met Éireann’s 1991–2020 averages.
36 frosts and 3 days of 25°C a year
Ground frosts, when the grass drops below 0°C, come on about 84 nights a year. Air frosts come mostly from October to April, most of all in February (about 7).
Air frosts by month
Average nights below 0°C
Ground frosts by month
Average nights with the grass below 0°C
Counted from Casement’s daily readings, 1991–2020, 36 km north-west of Newcastle: Met Éireann publishes these for its stations only. At that distance, read them as the area’s climate.
About 925 mm of rain a year
November is the wettest month and July the driest. 7th wettest of 10 towns of 2,500+ in County Wicklow. The wettest month brings about 2.0 times the rain of the driest. Casement records 1 mm or more on about 136 days a year, and 10 mm on about 18.
Rain by month
Millimetres
Sunshine by month
Hours, at Casement
Heating a home in Newcastle
84% 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 Newcastle’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 Casement comes by 26 April and the first by 2 November: about 190 frost-free days in between.
Highs of 17–27°C with lows of 8°C or more: Jun, Jul, Aug and Sep.
Parks & trails →Averages smooth over storms, floods and heatwaves; Newcastle’s hazards page covers the risks.
Flood & hazards →Met Éireann’s nearest station: Casement
Casement is 36 km north-west of Newcastle, the nearest of the 25 synoptic stations where Met Éireann records the weather around the clock. The station stands 91 m above sea level; Newcastle’s centre, 20 m.
| Month | High | Low | Rain | Air frosts | Sun (hours) |
|---|---|---|---|---|---|
| January | 8.2°C | 2.4°C | 65 mm | 6.7 | 54 |
| February | 8.5°C | 2.1°C | 55 mm | 7.2 | 75 |
| March | 10.3°C | 2.8°C | 49 mm | 5.7 | 107 |
| April | 12.6°C | 4.1°C | 52 mm | 3.1 | 157 |
| May | 15.4°C | 6.6°C | 56 mm | 0.8 | 190 |
| June | 18.0°C | 9.2°C | 66 mm | 0.0 | 167 |
| July | 19.7°C | 11.2°C | 60 mm | 0.0 | 153 |
| August | 19.4°C | 10.9°C | 71 mm | 0.0 | 153 |
| September | 17.2°C | 9.0°C | 61 mm | 0.1 | 125 |
| October | 13.7°C | 6.7°C | 82 mm | 1.3 | 102 |
| November | 10.4°C | 4.3°C | 82 mm | 4.0 | 67 |
| December | 8.4°C | 2.6°C | 76 mm | 7.2 | 48 |
| Year | 13.5°C | 6.0°C | 774 mm | 36 | 1,397 |
The table is Casement’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 Newcastle itself; the frosts, sunshine and degree days are this station’s.
How Newcastle 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 Wicklow.
Warmer than it used to be
Newcastle’s 1991–2020 average is 0.2°C warmer than 1981–2010’s. The biggest change is in February (+0.3°C).
A year’s rain is 925 mm, up 3% from 896 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.
Newcastle and its neighbours
Newtownmountkennedy has the coldest January nights next door (2.7°C, 0.8°C colder). 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 |
|---|---|---|---|
| Newcastle | 19.8°C | 3.5°C | 925 mm |
| Newtownmountkennedy 3.6 km | 19.3°C 0.5°C cooler | 2.7°C 0.8°C colder | 1,120 mm |
| Kilcoole 3.7 km | 19.7°C about the same | 3.6°C about the same | 907 mm |
| Kilpedder 5.1 km | 19.2°C 0.6°C cooler | 2.8°C 0.7°C colder | 1,085 mm |
| Greystones-Delgany 7.3 km | 19.7°C about the same | 3.5°C about the same | 912 mm |
| Ashford 7.9 km | 19.6°C about the same | 2.9°C 0.6°C colder | 1,086 mm |
| Rathnew 9.4 km | 19.7°C about the same | 3.3°C about the same | 1,007 mm |
Each town’s colour is Met Éireann’s 1 km grid at its own centre, so towns a few kilometres apart can differ.
Newcastle 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 | 8.9°C | 3.5°C | 6.2°C | 89 mm |
| February | 9.3°C | 3.4°C | 6.3°C | 67 mm |
| March | 10.7°C | 4.2°C | 7.5°C | 67 mm |
| April | 12.7°C | 5.6°C | 9.2°C | 64 mm |
| May | 15.2°C | 7.9°C | 11.6°C | 62 mm |
| June | 18.0°C | 10.4°C | 14.2°C | 65 mm |
| July | 19.8°C | 12.3°C | 16.0°C | 57 mm |
| August | 19.7°C | 12.2°C | 15.9°C | 69 mm |
| September | 17.7°C | 10.7°C | 14.2°C | 73 mm |
| October | 14.4°C | 8.3°C | 11.4°C | 103 mm |
| November | 11.3°C | 5.6°C | 8.4°C | 115 mm |
| December | 9.3°C | 4.0°C | 6.7°C | 95 mm |
| Year | 13.9°C | 7.3°C | 10.6°C | 925 mm |
How much a month can swing
December swings the most: over 30 years its average ranged from −0.5°C (2010) to 8.5°C (2015). July is the most reliable, staying within 3.7°C.
Where Newcastle’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 Newcastle’s population centre (0.4 km away).
- Weather station: the nearest of Met Éireann’s 25 synoptic stations, Casement, 36 km north-west, from Met Éireann’s station list.
- Frosts, sunshine, degree days: Casement’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 Newcastle’s climate
How warm does Newcastle get in summer?
The warmest month is July, when afternoons average 19.8°C.
How cold does Newcastle get in winter?
February nights average 3.4°C, the coldest of the year. At Casement, the nearest Met Éireann station, the air drops below 0°C on about 36 nights a year (1991–2020).
How much rain does Newcastle get?
About 925 mm a year, less than 51% of Irish towns. November is the wettest month (115 mm) and July the driest (57 mm).
How sunny is it?
Casement, 36 km north-west, averages about 1,397 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 Newcastle itself?
Partly. The temperatures and rain are Met Éireann’s 1991–2020 averages on its 1 km grid, read at Newcastle’s population centre; the frosts, degree days and year-to-year swings are those of Casement, 36 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 Newcastle’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 Newcastle →
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).