Nights stay kind in Porthmadog each January, milder than in 94% of UK towns
Midsummer highs settle at about 19.8°C (68°F). Expect the heaviest rain in January and the lightest in April. It is a wet place: more rain falls here than on 94% of UK towns. Frost greets about 29 mornings a year, so leave time to clear the car.
Met Office 1991–2020 averages for the town itself.
A year in Porthmadog at a glance
Each month’s typical high and low, in °C.
What a year in Porthmadog feels like
Typical highs and lows by season and by month, from the Met Office’s 1991–2020 averages.
About 1,329 mm of rain a year
January is the wettest month and April the driest. About 47 days a year bring 10 mm (0.4 in) or more. 5th wettest of 13 Gwynedd towns of 2,500+.
Rain by month
Millimetres
Sunshine by month
Hours of bright sunshine at Valley (Anglesey)
29 air frosts and 7 days of 25°C a year
On about 29 nights a year the air drops below freezing; days that stay below freezing are rare. About 7 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 Valley (Anglesey)
Valley (Anglesey) is 28 miles north-west of Porthmadog, 10 m (33 ft) above sea level. It is the nearest of the 37 long-running stations the Met Office publishes in full; at that distance read it for sunshine and the station’s own record, not as the town’s figures.
| Month | High | Low | Rain | Air frosts | Sun (hours) |
|---|---|---|---|---|---|
| January | 8.4°C | 3.8°C | 75 mm | 5.2 | 58 |
| February | 8.4°C | 3.6°C | 62 mm | 4.8 | 81 |
| March | 9.8°C | 4.5°C | 57 mm | 2.4 | 126 |
| April | 12.1°C | 6.1°C | 54 mm | 0.5 | 173 |
| May | 15.0°C | 8.6°C | 52 mm | 0.0 | 219 |
| June | 17.2°C | 11.0°C | 57 mm | 0.0 | 203 |
| July | 18.8°C | 12.9°C | 58 mm | 0.0 | 190 |
| August | 18.8°C | 13.1°C | 69 mm | 0.0 | 176 |
| September | 17.3°C | 11.6°C | 74 mm | 0.0 | 143 |
| October | 14.3°C | 9.2°C | 102 mm | 0.1 | 101 |
| November | 11.3°C | 6.6°C | 104 mm | 0.7 | 59 |
| December | 9.1°C | 4.4°C | 94 mm | 4.2 | 46 |
| Year | 13.4°C | 8.0°C | 857 mm | 18 | 1,575 |
Met Office historic station data, Valley, 1991–2020 months averaged (a month needs 20 of the 30 years; estimated values counted, missing months left out). Sunshine: Kipp & Zonen recorder.
How Porthmadog 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 Gwynedd 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 |
|---|---|---|---|
| Porthmadog | 19.8°C | 3.0°C | 1,329 mm |
| Penrhyndeudraeth 2.8 mi | 19.5°C about the same | 3.1°C about the same | 1,691 mm |
| Criccieth 4.2 mi | 19.4°C about the same | 3.6°C 0.6°C milder | 1,196 mm |
| Harlech 4.5 mi | 19.5°C about the same | 3.2°C about the same | 1,364 mm |
| Blaenau Ffestiniog 9.4 mi | 18.1°C 1.6°C cooler | 1.4°C 1.6°C colder | 2,332 mm |
| Penygroes 10.7 mi | 18.7°C 1.0°C cooler | 3.4°C about the same | 1,684 mm |
Porthmadog 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 | 8.0°C 46°F | 3.0°C 37°F | 5.6°C | 148 mm 5.8 in |
| February | 8.5°C 47°F | 3.0°C 37°F | 5.7°C | 101 mm 4.0 in |
| March | 10.5°C 51°F | 4.2°C 40°F | 7.4°C | 91 mm 3.6 in |
| April | 13.3°C 56°F | 5.9°C 43°F | 9.5°C | 74 mm 2.9 in |
| May | 16.2°C 61°F | 8.6°C 47°F | 12.4°C | 75 mm 2.9 in |
| June | 18.4°C 65°F | 10.8°C 51°F | 14.6°C | 89 mm 3.5 in |
| July | 19.8°C 68°F | 12.9°C 55°F | 16.3°C | 103 mm 4.0 in |
| August | 19.3°C 67°F | 12.4°C 54°F | 16.0°C | 104 mm 4.1 in |
| September | 18.0°C 64°F | 11.2°C 52°F | 14.6°C | 110 mm 4.3 in |
| October | 14.9°C 59°F | 8.8°C 48°F | 11.8°C | 143 mm 5.6 in |
| November | 11.4°C 53°F | 5.9°C 43°F | 8.7°C | 146 mm 5.7 in |
| December | 9.1°C 48°F | 3.8°C 39°F | 6.5°C | 144 mm 5.7 in |
| Year | 13.9°C | 7.5°C | 10.7°C | 1,329 mm |
Where Porthmadog’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 Porthmadog’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 Valley, 28 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 Porthmadog’s climate
How warm does Porthmadog get in summer?
July is the warmest month, with average highs of 19.8°C (68°F). About 7 days a year reach 25°C (77°F), fewer than 67% of UK towns.
How cold does Porthmadog get in winter?
February nights average 3.0°C (37°F). The air drops below freezing on about 29 nights a year, and about under 1 days a year stay below freezing all day.
How much rain does Porthmadog get?
About 1,329 mm (52 in) a year, more than 94% of UK towns. January is the wettest month (148 mm) and April the driest (74 mm).
How sunny is it?
The nearest Met Office station with a sunshine record, Valley (Anglesey) (28 miles away), averages 1,575 hours of bright sunshine a year. Sunshine isn’t on the town grid, so this is the station’s figure.
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 Porthmadog. 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 Porthmadog →
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.