Castletroy climate — normals and trends
Castletroy (Ireland) has a temperate oceanic climate (Cfb) under the Köppen-Geiger classification. Its mean annual temperature is 9.7 °C and it receives 979 mm of precipitation per year.
These figures are normals computed over 86 complete calendar years, from 1940 to 2025, using ERA5 reanalysis data from the Copernicus programme.
The warmest month is July (15.1 °C on average) and the coldest is January (5.0 °C). Rainfall peaks in December.
Castletroy averages 27 frost days, 0 hot days (≥ 30 °C) and 169 rainy days per year.
Castletroy has warmed by +0.4 °C between 1940 and 2025, or +0.05 °C per decade. This trend is statistically significant.
The number of frost days there went from about 33 to 21 per year over the period.
The hottest day of the period reached 30.5 °C (on 13 July 1983) and the coldest -11.1 °C (on 20 January 1940).
Data from ERA5 reanalysis (Copernicus Climate Change Service), redistributed under a CC-BY 4.0 licence. Normals are recomputed whenever the archive is updated.
Climate normals · ERA5
CastletroyMunster
- coords
- 52.67°, -8.55°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
9.7°C
Average daily high
12.7°C
Average daily low
6.8°C
Annual rainfall
979mm
Sunshine / day
6.9h
Mean relative humidity
83%
Average peak wind
19.4km/h
Seasonal range
10.1°C
Frost days (< 0 °C)
27 d/yr
Hot days (≥ 30 °C)
0 d/yr
Rainy days (≥ 1 mm)
169 d/yr
Annual snowfall
8.5 cm
Average feels-like high
10.2 °C
Average feels-like low
4.0 °C
Average peak gust
42.7 km/h
Tropical nights (≥ 20 °C)
0 d/yr
Solar radiation
9.4 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+0.4 °C
since 1940
+0.1 °C per decade · r² = 0.06 · p = 0.021
Trend fitted by linear regression (ordinary least squares) on annual means. A trend is shown only when it is statistically significant (p < 0.05).
A climograph overlays rainfall (bars) and temperature (line): the standard reading in climatology, where you can see at a glance whether the warm season is also the dry one.
Records for the period
Hottest day
30.5 °C
13 July 1983
Coldest day
-11.1 °C
20 January 1940
Wettest day
57 mm
25 August 1986
Windiest day
62.5 km/h
16 September 1961
Strongest gust
146.9 km/h
12 January 1974
Hottest feels-like
33.6 °C
13 July 1983
Coldest feels-like
-15.9 °C
20 January 1940
Snowiest day
15.0 cm
8 December 1954
Sunniest day
16.5 h
24 June 2018
Normals computed over complete calendar years 1940–2025.
A specific year
Pick a year and see how it compares to normal — warmer, drier or more extreme than usual?
Across the whole year
Month by month
| High | vs. normal | Precipitation | vs. normal | |
|---|---|---|---|---|
| Jan | 7.3 °C | -0.1 °C | 100 mm | +10 mm |
| Feb | 9.1 °C | +1.2 °C | 100 mm | +26 mm |
| Mar | 11.6 °C | +1.9 °C | 33 mm | -42 mm |
| Apr | 15.1 °C | +3.2 °C | 68 mm | -0 mm |
| May | 17.9 °C | +3.2 °C | 69 mm | -12 mm |
| Jun | 18.0 °C | +0.9 °C | 79 mm | +7 mm |
| Jul | 19.5 °C | +1.1 °C | 101 mm | +24 mm |
| Aug | 19.5 °C | +1.4 °C | 58 mm | -28 mm |
| Sep | 15.6 °C | -0.5 °C | 135 mm | +52 mm |
| Oct | 13.3 °C | +0.2 °C | 123 mm | +34 mm |
| Nov | 10.7 °C | +1.0 °C | 134 mm | +48 mm |
| Dec | 8.8 °C | +0.8 °C | 89 mm | -8 mm |
The year's extremes
What was the weather like that day?
Your birthday, a wedding, a memorable trip: discover the actual weather for any date since 1940.
Frequently asked questions
What is the climate of Castletroy?
Castletroy has a temperate oceanic climate (Köppen Cfb). Over 1940-2025, the average annual temperature is 9.7 °C and it receives 979 mm of precipitation per year.
What is the hottest day ever recorded in Castletroy?
The hottest day measured in Castletroy between 1940 and 2025 was 13 July 1983, reaching 30.5 °C.
What is the coldest day in Castletroy?
The coldest day measured in Castletroy between 1940 and 2025 was 20 January 1940, at -11.1 °C.
Does it snow in Castletroy?
Yes. Castletroy gets on average 8.5 cm of snow per year and has around 27 frost days.
Has the climate of Castletroy warmed?
Yes: Castletroy warmed by +0.4 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Castletroy?
The wettest day measured in Castletroy between 1940 and 2025 was 25 August 1986, with 57 mm of rain in 24 hours.
What was the windiest day in Castletroy?
The windiest day measured in Castletroy between 1940 and 2025 was 16 September 1961, with winds reaching 62.5 km/h.
What is the warmest month in Castletroy?
The warmest month in Castletroy is July (15.1 °C on average); the coldest is January (5.0 °C).
How much does it rain in Castletroy?
Castletroy receives on average 979 mm of precipitation per year, spread over about 169 rainy days.
Is it sunny in Castletroy?
Castletroy gets on average 6.9 hours of sunshine per day, roughly 2,519 hours per year over 1940-2025.
What is the biggest single-day snowfall in Castletroy?
The heaviest 24-hour snowfall measured in Castletroy between 1940 and 2025 was 8 December 1954, with 15.0 cm.
Are there tropical nights in Castletroy?
Almost never: tropical nights (temperature staying above 20 °C) are virtually non-existent in Castletroy.
What was the most extreme apparent temperature in Castletroy?
In Castletroy, between 1940 and 2025, the highest apparent temperature reached 33.6 °C on 13 July 1983, and the lowest was -15.9 °C on 20 January 1940.
Compare Castletroy with another city
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Nearby cities
The climate around Castletroy