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Castlereagh, Northern Ireland climate
Cfb Oceanic / temperate
Castlereagh has a mildly seasonal cool-temperate climate (Oceanic / temperate, Köppen Cfb). The hottest month is July with an average daily high near 19°C, while the coldest is January averaging around 2°C at night. Precipitation is fairly even year-round, totalling about 981 mm. At latitude 55°N, day length swings from 7.0 hours in midwinter to 17.0 hours at midsummer.
Temperature & precipitation
Daily high–low temperature range with the monthly average, plus monthly precipitation · 1991–2020 normals · hover a month for the exact figuresClear vs cloudy days
Share of days each month that are clear, partly cloudy or cloudy · 1991–2020 · hover a month for the day countsCastlereagh climate normals (1991–2020)
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°C) | 8 | 9 | 10 | 13 | 15 | 18 | 19 | 19 | 17 | 14 | 10 | 8 |
| Avg temp (°C) | 5 | 6 | 7 | 9 | 11 | 14 | 15 | 15 | 13 | 11 | 8 | 6 |
| Avg low (°C) | 2 | 2 | 3 | 5 | 7 | 10 | 12 | 12 | 10 | 7 | 5 | 3 |
| Precipitation (mm) | 89 | 73 | 73 | 64 | 68 | 74 | 77 | 88 | 75 | 98 | 106 | 95 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Avg high (°C) | 8 | 9 | 10 | 13 | 15 | 18 |
| Avg temp (°C) | 5 | 6 | 7 | 9 | 11 | 14 |
| Avg low (°C) | 2 | 2 | 3 | 5 | 7 | 10 |
| Precipitation (mm) | 89 | 73 | 73 | 64 | 68 | 74 |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Avg high (°C) | 19 | 19 | 17 | 14 | 10 | 8 |
| Avg temp (°C) | 15 | 15 | 13 | 11 | 8 | 6 |
| Avg low (°C) | 12 | 12 | 10 | 7 | 5 | 3 |
| Precipitation (mm) | 77 | 88 | 75 | 98 | 106 | 95 |
How often — frequency of weather events
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Days with measurable rain (days) | 20 | 17 | 18 | 16 | 16 | 14 | 16 | 18 | 16 | 18 | 21 | 20 |
| Days with low ≤ 0°C (days) | 6 | 5 | 4 | 1 | 0.0 | — | — | — | — | 0.1 | 2 | 5 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Days with measurable rain (days) | 20 | 17 | 18 | 16 | 16 | 14 |
| Days with low ≤ 0°C (days) | 6 | 5 | 4 | 1 | 0.0 | — |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Days with measurable rain (days) | 16 | 18 | 16 | 18 | 21 | 20 |
| Days with low ≤ 0°C (days) | — | — | — | 0.1 | 2 | 5 |
Sky & atmosphere
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Cloud cover (%) | 79 | 79 | 78 | 76 | 73 | 77 | 78 | 77 | 76 | 78 | 79 | 78 |
| Clear days (≤ 30% cloud) | 1 | 1 | 1 | 1 | 2 | 2 | 1 | 1 | 1 | 0.8 | 1 | 1 |
| Partly cloudy days (30–70%) | 7 | 7 | 8 | 8 | 9 | 7 | 7 | 9 | 9 | 8 | 7 | 7 |
| Cloudy days (≥ 70%) | 22 | 20 | 22 | 20 | 20 | 21 | 23 | 21 | 20 | 22 | 22 | 23 |
| Relative humidity (%) | 90 | 90 | 89 | 86 | 85 | 85 | 86 | 87 | 88 | 88 | 90 | 91 |
| Wind speed (km/h) | 21.8 | 21.1 | 18.9 | 16.5 | 15.0 | 13.7 | 13.2 | 14.1 | 16.5 | 19.2 | 20.5 | 21.1 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 79 | 79 | 78 | 76 | 73 | 77 |
| Clear days (≤ 30% cloud) | 1 | 1 | 1 | 1 | 2 | 2 |
| Partly cloudy days (30–70%) | 7 | 7 | 8 | 8 | 9 | 7 |
| Cloudy days (≥ 70%) | 22 | 20 | 22 | 20 | 20 | 21 |
| Relative humidity (%) | 90 | 90 | 89 | 86 | 85 | 85 |
| Wind speed (km/h) | 21.8 | 21.1 | 18.9 | 16.5 | 15.0 | 13.7 |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 78 | 77 | 76 | 78 | 79 | 78 |
| Clear days (≤ 30% cloud) | 1 | 1 | 1 | 0.8 | 1 | 1 |
| Partly cloudy days (30–70%) | 7 | 9 | 9 | 8 | 7 | 7 |
| Cloudy days (≥ 70%) | 23 | 21 | 20 | 22 | 22 | 23 |
| Relative humidity (%) | 86 | 87 | 88 | 88 | 90 | 91 |
| Wind speed (km/h) | 13.2 | 14.1 | 16.5 | 19.2 | 20.5 | 21.1 |
Methodology & sources
Temperature & precipitation — 1991–2020 normals computed from 29 years of daily observations at Stormont Castle, a weather station, about 5 km from the city centre. The underlying daily records come from NOAA's global station network.
Cloud, humidity, wind & sunshine — modelled estimates from NASA POWER, NASA's satellite-and-reanalysis climatology. This is the standard global source for atmospheric variables, which are not measured at most weather stations.