Photo: John Lord · CC BY-SA 2.0Porth is among the wettest of UK towns: 2,153 mm (85 in) of rain a year
July afternoons average 19.9°C (68°F). Of all months, December brings the most rain and May the least. Summers stay cool: July afternoons here are cooler than in 76% of UK towns. Frost greets about 43 mornings a year, so leave time to clear the car.
Met Office 1991–2020 averages for the town itself.
A year in Porth at a glance
Each month’s typical high and low, in °C.
What a year in Porth feels like
Typical highs and lows by season and by month, from the Met Office’s 1991–2020 averages.
About 2,153 mm of rain a year
December is the wettest month and May the driest. About 71 days a year bring 10 mm (0.4 in) or more. 6th wettest of 32 Mid Glamorgan towns of 2,500+.
Rain by month
Millimetres
43 air frosts and 8 days of 25°C a year
On about 43 nights a year the air drops below freezing, and on about 2 days it stays below freezing all day. About 8 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 13 miles south-east of Porth, 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 Porth 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 |
|---|---|---|---|
| Porth | 19.9°C | 1.7°C | 2,153 mm |
| Wattstown 1.7 mi | 20.0°C about the same | 1.5°C about the same | 2,114 mm |
| Tonypandy 1.9 mi | 20.1°C about the same | 1.5°C about the same | 2,101 mm |
| Tylorstown and Pontygwaith 2.4 mi | 20.0°C about the same | 1.5°C about the same | 2,114 mm |
| Tonyrefail 2.4 mi | 20.6°C 0.6°C warmer | 1.6°C about the same | 1,865 mm |
| Ynysybwl 2.6 mi | 20.3°C about the same | 1.9°C about the same | 1,800 mm |
| Gilfach Goch 3.2 mi | 20.1°C about the same | 0.8°C 0.9°C colder | 2,103 mm |
Porth 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 | 7.4°C 45°F | 1.7°C 35°F | 4.6°C | 235 mm 9.2 in |
| February | 7.2°C 45°F | 1.0°C 34°F | 4.0°C | 189 mm 7.4 in |
| March | 9.3°C 49°F | 2.0°C 36°F | 5.7°C | 157 mm 6.2 in |
| April | 12.4°C 54°F | 3.7°C 39°F | 8.1°C | 122 mm 4.8 in |
| May | 15.5°C 60°F | 6.4°C 43°F | 10.9°C | 120 mm 4.7 in |
| June | 18.2°C 65°F | 9.3°C 49°F | 13.8°C | 129 mm 5.1 in |
| July | 19.9°C 68°F | 11.1°C 52°F | 15.5°C | 130 mm 5.1 in |
| August | 19.5°C 67°F | 11.0°C 52°F | 15.3°C | 160 mm 6.3 in |
| September | 17.1°C 63°F | 8.9°C 48°F | 13.0°C | 157 mm 6.2 in |
| October | 13.3°C 56°F | 6.3°C 43°F | 9.8°C | 239 mm 9.4 in |
| November | 9.8°C 50°F | 3.6°C 39°F | 6.7°C | 236 mm 9.3 in |
| December | 7.4°C 45°F | 1.7°C 35°F | 4.5°C | 279 mm 11.0 in |
| Year | 13.1°C | 5.6°C | 9.3°C | 2,153 mm |
Where Porth’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 Porth’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, 13 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 Porth’s climate
How warm does Porth get in summer?
July is the warmest month, with average highs of 19.9°C (68°F). About 8 days a year reach 25°C (77°F), fewer than 65% of UK towns.
How cold does Porth get in winter?
February nights average 1.0°C (34°F). The air drops below freezing on about 43 nights a year, and about 2 days a year stay below freezing all day.
How much rain does Porth get?
About 2,153 mm (85 in) a year, more than almost every UK town. December is the wettest month (279 mm) and May the driest (120 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 Porth. 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 Porth →
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.