Photo: David Medcalf · CC BY-SA 2.0Llanllyfni is among the wettest of UK towns: 1,700 mm (67 in) of rain a year
On a normal July day the thermometer tops out near 18.7°C (66°F). By January nights alone, it runs milder than 96% of UK towns. Temperatures cover 16°C across the year, low to high. Picnics, hikes and garden evenings come into their own from June to August, with highs of 17–19°C.
Met Office 1991–2020 averages for the town itself.
A year in Llanllyfni at a glance
Each month’s typical high and low, in °C.
What a year in Llanllyfni feels like
Typical highs and lows by season and by month, from the Met Office’s 1991–2020 averages.
About 1,700 mm of rain a year
November is the wettest month and May the driest. About 60 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)
20 air frosts and 4 days of 25°C a year
On about 20 nights a year the air drops below freezing; days that stay below freezing are rare. 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 Valley (Anglesey)
Valley (Anglesey) is 18 miles north-west of Llanllyfni, 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 Llanllyfni 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 |
|---|---|---|---|
| Llanllyfni | 18.7°C | 3.3°C | 1,700 mm |
| Penygroes 0.8 mi | 18.7°C about the same | 3.4°C about the same | 1,684 mm |
| Caernarfon 6.7 mi | 19.6°C 0.9°C warmer | 3.4°C about the same | 1,426 mm |
| Llanrug 8.2 mi | 19.3°C 0.5°C warmer | 3.1°C about the same | 1,597 mm |
| Llanberis 8.3 mi | 17.6°C 1.1°C cooler | 2.6°C 0.7°C colder | 2,530 mm |
| Criccieth 8.7 mi | 19.4°C 0.6°C warmer | 3.6°C about the same | 1,196 mm |
| Bethel 9.1 mi | 19.3°C 0.5°C warmer | 3.1°C about the same | 1,569 mm |
Llanllyfni 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 | 3.3°C 38°F | 5.7°C | 172 mm 6.8 in |
| February | 8.1°C 47°F | 3.1°C 38°F | 5.7°C | 132 mm 5.2 in |
| March | 9.6°C 49°F | 4.0°C 39°F | 6.8°C | 118 mm 4.6 in |
| April | 12.2°C 54°F | 5.7°C 42°F | 8.8°C | 100 mm 3.9 in |
| May | 15.1°C 59°F | 8.3°C 47°F | 11.6°C | 95 mm 3.7 in |
| June | 17.3°C 63°F | 10.7°C 51°F | 13.9°C | 108 mm 4.2 in |
| July | 18.7°C 66°F | 12.6°C 55°F | 15.5°C | 123 mm 4.9 in |
| August | 18.6°C 66°F | 12.6°C 55°F | 15.6°C | 139 mm 5.5 in |
| September | 16.8°C 62°F | 11.0°C 52°F | 13.9°C | 138 mm 5.4 in |
| October | 13.8°C 57°F | 8.6°C 47°F | 11.2°C | 192 mm 7.6 in |
| November | 10.7°C 51°F | 5.9°C 43°F | 8.4°C | 196 mm 7.7 in |
| December | 8.5°C 47°F | 3.8°C 39°F | 6.3°C | 189 mm 7.4 in |
| Year | 13.1°C | 7.5°C | 10.3°C | 1,700 mm |
Where Llanllyfni’s numbers come from
Averages over 30 years, not a forecast.
- Mean temperature, rain and day counts: HadUK-Grid 1991–2020 averages for the 1 Met Office 2 km grid square whose centre lies inside Llanllyfni’s built-up area.
- 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 Llanllyfni’s climate
How warm does Llanllyfni get in summer?
July is the warmest month, with average highs of 18.7°C (66°F). About 4 days a year reach 25°C (77°F), fewer than 83% of UK towns.
How cold does Llanllyfni get in winter?
February nights average 3.1°C (38°F). The air drops below freezing on about 20 nights a year, and about under 1 days a year stay below freezing all day.
How much rain does Llanllyfni get?
About 1,700 mm (67 in) a year, more than 98% of UK towns. November is the wettest month (196 mm) and May the driest (95 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 Llanllyfni. 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 Llanllyfni →
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.