Trefor is among the least frosty of UK towns
Peak summer warmth arrives in July, with afternoons near 18.7°C (66°F). The seasons sit close together: from a winter night to a summer afternoon the average spans only 15°C. Its yearly rainfall tops that of 96% of UK towns. Homes need heating from November to April, the months averaging under 10°C.
Met Office 1991–2020 averages for the town itself.
A year in Trefor at a glance
Each month’s typical high and low, in °C.
What a year in Trefor feels like
Typical highs and lows by season and by month, from the Met Office’s 1991–2020 averages.
About 1,474 mm of rain a year
November is the wettest month and May the driest. About 49 days a year bring 10 mm (0.4 in) or more.
Rain by month
Millimetres
Sunshine by month
Hours of bright sunshine at Valley (Anglesey)
15 air frosts and 2 days of 25°C a year
On about 15 nights a year the air drops below freezing; days that stay below freezing are rare. About 2 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 18 miles north of Trefor, 10 m (33 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 | 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 Trefor 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 |
|---|---|---|---|
| Trefor | 18.7°C | 3.5°C | 1,474 mm |
| Nefyn 5.7 mi | 18.2°C 0.6°C cooler | 3.4°C about the same | 1,220 mm |
| Penygroes 7.2 mi | 18.7°C about the same | 3.4°C about the same | 1,684 mm |
| Pwllheli 7.3 mi | 18.9°C about the same | 3.8°C about the same | 1,219 mm |
| Criccieth 9.5 mi | 19.4°C 0.6°C warmer | 3.6°C about the same | 1,196 mm |
Trefor 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 | 3.5°C 38°F | 5.7°C | 130 mm 5.1 in |
| February | 8.4°C 47°F | 3.6°C 38°F | 6.0°C | 113 mm 4.4 in |
| March | 9.8°C 50°F | 4.3°C 40°F | 7.1°C | 104 mm 4.1 in |
| April | 12.4°C 54°F | 5.9°C 43°F | 9.0°C | 91 mm 3.6 in |
| May | 15.1°C 59°F | 8.3°C 47°F | 11.6°C | 84 mm 3.3 in |
| June | 17.3°C 63°F | 10.7°C 51°F | 13.9°C | 96 mm 3.8 in |
| July | 18.7°C 66°F | 12.5°C 54°F | 15.5°C | 111 mm 4.4 in |
| August | 18.8°C 66°F | 12.7°C 55°F | 15.7°C | 120 mm 4.7 in |
| September | 17.1°C 63°F | 11.2°C 52°F | 14.1°C | 120 mm 4.7 in |
| October | 14.2°C 58°F | 9.0°C 48°F | 11.6°C | 169 mm 6.6 in |
| November | 11.2°C 52°F | 6.4°C 44°F | 8.8°C | 174 mm 6.9 in |
| December | 9.1°C 48°F | 4.4°C 40°F | 6.8°C | 163 mm 6.4 in |
| Year | 13.3°C | 7.7°C | 10.5°C | 1,474 mm |
Where Trefor’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 Trefor’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, 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 Trefor’s climate
How warm does Trefor get in summer?
August is the warmest month, with average highs of 18.8°C (66°F). About 2 days a year reach 25°C (77°F), fewer than 95% of UK towns.
How cold does Trefor get in winter?
January nights average 3.5°C (38°F). The air drops below freezing on about 15 nights a year, and about under 1 days a year stay below freezing all day.
How much rain does Trefor get?
About 1,474 mm (58 in) a year, more than 96% of UK towns. November is the wettest month (174 mm) and May the driest (84 mm).
How sunny is it?
The nearest Met Office station with a sunshine record, Valley (Anglesey) (18 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 Trefor. 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 Trefor →
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.