Photo: Jaggery · CC BY-SA 2.0Hardly any UK towns collect more rain than Treorchy: 2,503 mm (99 in) a year
A clear January night here typically dips to 1.6°C (35°F). Expect the heaviest rain in December and the lightest in May. In July, afternoons here are cooler than in 97% of UK towns. Gritters and ice scrapers earn their keep on roughly 49 nights a year below 0°C.
Met Office 1991–2020 averages for the town itself.
A year in Treorchy at a glance
Each month’s typical high and low, in °C.
What a year in Treorchy feels like
Typical highs and lows by season and by month, from the Met Office’s 1991–2020 averages.
About 2,503 mm of rain a year
December is the wettest month and May the driest. About 83 days a year bring 10 mm (0.4 in) or more. 2nd wettest of 32 Mid Glamorgan towns of 2,500+.
Rain by month
Millimetres
49 air frosts and 4 days of 25°C a year
On about 49 nights a year the air drops below freezing, and on about 2 days it stays below freezing all day. About 4 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 18 miles south-east of Treorchy, 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 Treorchy 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 Mid Glamorgan 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 |
|---|---|---|---|
| Treorchy | 18.4°C | 1.6°C | 2,503 mm |
| Maerdy 1.5 mi | 19.5°C 1.1°C warmer | 1.0°C 0.6°C colder | 2,411 mm |
| Treherbert 1.6 mi | 18.0°C about the same | 1.2°C about the same | 2,687 mm |
| Rhondda 1.9 mi | 19.5°C 1.1°C warmer | 1.7°C about the same | 2,402 mm |
| Ferndale 2.7 mi | 19.5°C 1.1°C warmer | 1.2°C about the same | 2,382 mm |
| Nant-y-moel 3.0 mi | 18.4°C about the same | 1.5°C about the same | 2,478 mm |
| Tylorstown and Pontygwaith 3.5 mi | 20.0°C 1.6°C warmer | 1.5°C about the same | 2,114 mm |
Treorchy 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 | 6.8°C 44°F | 1.6°C 35°F | 4.2°C | 284 mm 11.2 in |
| February | 6.3°C 43°F | 0.8°C 34°F | 3.6°C | 197 mm 7.8 in |
| March | 8.4°C 47°F | 1.9°C 35°F | 5.2°C | 178 mm 7.0 in |
| April | 11.1°C 52°F | 3.3°C 38°F | 7.3°C | 139 mm 5.5 in |
| May | 14.4°C 58°F | 6.2°C 43°F | 10.3°C | 135 mm 5.3 in |
| June | 16.7°C 62°F | 8.5°C 47°F | 12.6°C | 150 mm 5.9 in |
| July | 18.4°C 65°F | 10.6°C 51°F | 14.6°C | 184 mm 7.3 in |
| August | 18.0°C 64°F | 10.6°C 51°F | 14.3°C | 204 mm 8.0 in |
| September | 15.9°C 61°F | 8.7°C 48°F | 12.3°C | 192 mm 7.6 in |
| October | 12.3°C 54°F | 6.1°C 43°F | 9.2°C | 273 mm 10.8 in |
| November | 8.8°C 48°F | 3.5°C 38°F | 6.1°C | 270 mm 10.6 in |
| December | 6.7°C 44°F | 1.6°C 35°F | 4.1°C | 295 mm 11.6 in |
| Year | 12.0°C | 5.3°C | 8.6°C | 2,503 mm |
Where Treorchy’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 Treorchy’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, 18 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 Treorchy’s climate
How warm does Treorchy get in summer?
July is the warmest month, with average highs of 18.4°C (65°F). About 4 days a year reach 25°C (77°F), fewer than 79% of UK towns.
How cold does Treorchy get in winter?
February nights average 0.8°C (34°F). The air drops below freezing on about 49 nights a year, and about 2 days a year stay below freezing all day.
How much rain does Treorchy get?
About 2,503 mm (99 in) a year, more than almost every UK town. December is the wettest month (295 mm) and May the driest (135 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 Treorchy. 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 Treorchy →
Contains public sector information licensed under the Open Government Licence v3.0. Contains HM Land Registry data © Crown copyright and database right 2026. Contains OS data © Crown copyright and database right 2026 (ONS boundaries). Northern Ireland: Source: NISRA; contains Land & Property Services data and Ordnance Survey of Northern Ireland information, © Crown copyright, licensed under the Open Government Licence v3.0. Scotland: contains National Records of Scotland data, Registers of Scotland data and SEPA data, © Crown copyright / © SEPA 2025, licensed under the Open Government Licence v3.0.