More rain falls on Castleton than on 91% of UK towns: 1,228 mm (48 in) a year
In January the night’s low is typically 2.2°C (36°F). December is the wettest month, April the driest. Winters are mild: January nights here are milder than in 74% of UK towns. Keep the boiler serviced for the months from November to April, which average under 10°C.
Met Office 1991–2020 averages for the town itself.
A year in Castleton at a glance
Each month’s typical high and low, in °C.
What a year in Castleton feels like
Typical highs and lows by season and by month, from the Met Office’s 1991–2020 averages.
About 1,228 mm of rain a year
December is the wettest month and April the driest. About 41 days a year bring 10 mm (0.4 in) or more.
Rain by month
Millimetres
35 air frosts and 9 days of 25°C a year
On about 35 nights a year the air drops below freezing, and on about under 1 days it stays below freezing all day. About 9 days a year reach 25°C (77°F).
Day counts are 1991–2020 averages from the Met Office’s 2 km grid. The Met Office calls a day of 25°C or more a summer day and a night below 0°C an air frost; ground frosts, on grass, come more often.
The Met Office station at Cardiff Bute Park
Cardiff Bute Park is 6.0 miles south-west of Castleton, 9 m (30 ft) above sea level. It is the nearest of the 37 long-running stations the Met Office publishes in full.
| Month | High | Low | Rain | Air frosts |
|---|---|---|---|---|
| January | 8.6°C | 2.5°C | 127 mm | 8.1 |
| February | 9.1°C | 2.5°C | 93 mm | 7.5 |
| March | 11.3°C | 3.9°C | 85 mm | 3.9 |
| April | 14.4°C | 5.7°C | 72 mm | 1.4 |
| May | 17.4°C | 8.5°C | 78 mm | 0.0 |
| June | 20.1°C | 11.3°C | 73 mm | 0.0 |
| July | 21.8°C | 13.1°C | 84 mm | 0.0 |
| August | 21.4°C | 12.9°C | 105 mm | 0.0 |
| September | 19.1°C | 10.7°C | 87 mm | 0.0 |
| October | 15.2°C | 8.0°C | 128 mm | 1.0 |
| November | 11.6°C | 4.9°C | 131 mm | 3.7 |
| December | 9.1°C | 2.9°C | 140 mm | 8.3 |
| Year | 14.9°C | 7.2°C | 1,201 mm | 34 |
Met Office historic station data, Cardiff Bute Park, 1991–2020 months averaged (a month needs 20 of the 30 years; estimated values counted, missing months left out). Sunshine: Campbell-Stokes recorder.
How Castleton compares
Against the 2,537 towns and cities of 2,500 or more across the UK, each with its own Met Office averages, and its place among Gwent towns that size.
Nearby towns’ climate
The nearest towns of 1,000+ within 12 miles: a hill, a valley or the sea can make a real difference over a few miles.
| Town | July high | January low | Rain a year |
|---|---|---|---|
| Castleton | 21.7°C | 2.2°C | 1,228 mm |
| Marshfield 0.9 mi | 21.7°C about the same | 2.7°C 0.5°C milder | 1,214 mm |
| Rogerstone 3.6 mi | 21.5°C about the same | 2.1°C about the same | 1,242 mm |
| Machen 4.4 mi | 20.8°C 0.9°C cooler | 1.2°C 1.0°C colder | 1,454 mm |
| Risca 4.8 mi | 21.4°C about the same | 1.7°C about the same | 1,372 mm |
| Newport 5.0 mi | 22.1°C about the same | 2.7°C about the same | 1,080 mm |
| Trethomas 5.1 mi | 21.0°C 0.7°C cooler | 1.9°C about the same | 1,444 mm |
Castleton weather by month
Average daily high and low, mean temperature and rain, 1991–2020, for the town itself (the Met Office’s HadUK-Grid).
| Month | High | Low | Mean | Rain |
|---|---|---|---|---|
| January | 7.9°C 46°F | 2.2°C 36°F | 5.0°C | 132 mm 5.2 in |
| February | 8.5°C 47°F | 2.2°C 36°F | 5.3°C | 100 mm 3.9 in |
| March | 10.9°C 52°F | 3.5°C 38°F | 7.2°C | 87 mm 3.4 in |
| April | 13.9°C 57°F | 5.2°C 41°F | 9.5°C | 73 mm 2.9 in |
| May | 17.0°C 63°F | 7.9°C 46°F | 12.5°C | 75 mm 3.0 in |
| June | 19.8°C 68°F | 10.8°C 51°F | 15.3°C | 73 mm 2.9 in |
| July | 21.7°C 71°F | 12.5°C 55°F | 17.1°C | 82 mm 3.2 in |
| August | 21.2°C 70°F | 12.5°C 54°F | 16.8°C | 102 mm 4.0 in |
| September | 18.7°C 66°F | 10.4°C 51°F | 14.5°C | 89 mm 3.5 in |
| October | 14.6°C 58°F | 7.9°C 46°F | 11.3°C | 134 mm 5.3 in |
| November | 11.0°C 52°F | 4.8°C 41°F | 7.9°C | 134 mm 5.3 in |
| December | 8.5°C 47°F | 2.8°C 37°F | 5.6°C | 148 mm 5.8 in |
| Year | 14.5°C | 6.9°C | 10.7°C | 1,228 mm |
Where Castleton’s numbers come from
Averages over 30 years, not a forecast.
- Mean temperature, rain and day counts: HadUK-Grid 1991–2020 averages for the Met Office 2 km grid square nearest Castleton’s centre (the town is smaller than one square).
- Highs and lows: the Met Office publishes average daily maxima and minima on its 12 km grid; each is moved by the difference between the town’s 2 km mean temperature and the 12 km square’s, which carries the town’s own height and setting over.
- Weather station and sunshine: Met Office historic station data for Cardiff Bute Park, 6.0 miles away, months of 1991–2020 averaged.
- Comparisons: every town and city of 2,500 or more across the UK, all four nations, read the same way.
Met Office HadUK-Grid · Met Office Climate Data Portal · Historic station data. Open Government Licence v3.0.
Questions about Castleton’s climate
How warm does Castleton get in summer?
July is the warmest month, with average highs of 21.7°C (71°F). About 9 days a year reach 25°C (77°F), fewer than 58% of UK towns.
How cold does Castleton get in winter?
January nights average 2.2°C (36°F). The air drops below freezing on about 35 nights a year, and about under 1 days a year stay below freezing all day.
How much rain does Castleton get?
About 1,228 mm (48 in) a year, more than 91% of UK towns. December is the wettest month (148 mm) and April the driest (73 mm).
Where do these figures come from?
The Met Office’s HadUK-Grid 1991–2020 averages, which turn thousands of weather stations into a map of the UK in 2 km squares; the page reads the squares inside Castleton. They are 30-year averages, not a forecast.
Contains Met Office data © Crown copyright 2026, Open Government Licence v3.0. HadUK-Grid 1991–2020 averages via the Met Office Climate Data Portal; station averages from Met Office historic station data. Today’s forecast for Castleton →
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