Saint-Thonan is among the mainland French towns with the fewest days of 25 degrees or more
Deep winter brings January lows near 4.4°C. In January, nights here are milder than in 95% of mainland French towns. A year here swings 18°C from midwinter lows to midsummer highs. Keep the boiler serviced for the months from November to April, which average under 10°C.
Figures from Météo-France’s Ploudaniel-Inrae station, 2.8 km north.
A year in Saint-Thonan at a glance
Each month’s typical high and low in °C, at the Ploudaniel-Inrae station.
What a year in Saint-Thonan feels like
Typical highs and lows by season and by month, from Météo-France’s 1991–2020 normals at Ploudaniel-Inrae.
About 1,147 mm of rain a year
December is the wettest month and June the driest. About 37 days a year bring 10 mm or more. 44th wettest of 91 towns of 2,500+ in Finistère.
Rain by month
Millimeters
Sunshine by month
Hours of sunshine at Brest-Guipavas
21 frosts and 13 days of 25°C a year
On about 21 nights a year the air drops to 0°C or below; days that stay below freezing are rare. About 13 days a year reach 25°C, and 1 reach 30°C.
Day counts are Météo-France’s 1991–2020 normals at Ploudaniel-Inrae: a frost is a night of 0°C or below, a summer day (jour d’été) 25°C or more, a hot day (forte chaleur) 30°C or more.
The Météo-France station at Ploudaniel-Inrae
Ploudaniel-Inrae is 2.8 km north of Saint-Thonan. Every figure on this page is the station’s, not a measurement in Saint-Thonan itself.
| Station (Météo-France number) | Ploudaniel-Inrae (29179001) |
| Distance from the town | 2.8 km north |
| Station altitude | 76 m |
| Town altitude (its center) | 89 m |
| Period | 1991–2020 |
| Sunshine measured at | Brest-Guipavas, 5.1 km away |
TownRatings matches each commune to one station with at least 24 years of temperature and rain records: the nearest, counting every 100 m of height difference as 10 km, never across the sea.
How Saint-Thonan compares
Against the 4,385 towns of 2,500 or more in mainland France, each read from its own matched station. The dots are the other towns of 2,500+ in Finistère.
Nearby towns’ climate
The nearest towns of 2,500+ within 29 km. Where a neighbor uses the same station its figures are the same: the differences you’d feel over a few kilometers aren’t in the normals.
| Town | Station | July high | January low | Rain a year |
|---|---|---|---|---|
| Saint-Thonan | Ploudaniel-Inrae | 21.3°C | 4.4°C | 1,147 mm |
| Ploudaniel 6.1 km | same station | 21.3°C about the same | 4.4°C about the same | 1,147 mm |
| Landerneau 6.2 km | same station | 21.3°C about the same | 4.4°C about the same | 1,147 mm |
| Plouédern 6.4 km | same station | 21.3°C about the same | 4.4°C about the same | 1,147 mm |
| Plabennec 7.2 km | Brest-Guipavas | 20.8°C 0.5°C cooler | 4.6°C about the same | 1,230 mm |
| Guipavas 8.1 km | Brest-Guipavas | 20.8°C 0.5°C cooler | 4.6°C about the same | 1,230 mm |
| Le Relecq-Kerhuon 9.6 km | Brest-Guipavas | 20.8°C 0.5°C cooler | 4.6°C about the same | 1,230 mm |
Saint-Thonan weather by month
Average daily high and low, mean temperature and rain, 1991–2020, at the Ploudaniel-Inrae station; sunshine at Brest-Guipavas.
| Month | High | Low | Mean | Rain | Sun (hours) |
|---|---|---|---|---|---|
| January | 9.8°C | 4.4°C | 7.1°C | 132 mm | 61 |
| February | 10.2°C | 3.9°C | 7.1°C | 111 mm | 82 |
| March | 12.2°C | 4.9°C | 8.5°C | 77 mm | 122 |
| April | 14.1°C | 5.6°C | 9.9°C | 84 mm | 165 |
| May | 17.0°C | 8.4°C | 12.7°C | 71 mm | 188 |
| June | 19.5°C | 10.8°C | 15.1°C | 60 mm | 184 |
| July | 21.3°C | 12.5°C | 16.9°C | 64 mm | 180 |
| August | 21.5°C | 12.5°C | 17.0°C | 68 mm | 172 |
| September | 19.8°C | 10.6°C | 15.2°C | 69 mm | 158 |
| October | 16.3°C | 9.0°C | 12.7°C | 122 mm | 109 |
| November | 12.7°C | 6.6°C | 9.7°C | 143 mm | 72 |
| December | 10.4°C | 4.8°C | 7.6°C | 147 mm | 61 |
| Year | 15.4°C | 7.8°C | 11.6°C | 1,147 mm | 1,555 |
Where Saint-Thonan’s numbers come from
Averages over 30 years, not a forecast.
- Temperature, rain and day counts: Météo-France’s fiche climatologique for Ploudaniel-Inrae, 2.8 km away: statistics for 1991–2020.
- Which station: among stations with at least 24 of the 30 years of temperature and rain, the nearest to the commune’s population-weighted center, counting each 100 m of height difference as 10 km; mainland towns use mainland stations and each overseas département its own.
- Altitudes: the town’s from IGN’s RGE ALTI® at its population-weighted center; the station’s from Météo-France.
- Sunshine: the nearest station with at least 10 years of sunshine records, Brest-Guipavas, 5.1 km away.
- Comparisons: every town of 2,500 or more in mainland France, read the same way; the dots are the towns of 2,500+ in Finistère.
Météo-France fiches climatologiques · IGN RGE ALTI®. Licence Ouverte 2.0.
Questions about Saint-Thonan’s climate
How warm does Saint-Thonan get in summer?
August is the warmest month, with average highs of 21.5°C. About 13 days a year reach 25°C, fewer than 98% of mainland French towns, and about 1 reach 30°C.
How cold does Saint-Thonan get in winter?
February nights average 3.9°C. The air drops to 0°C or below on about 21 nights a year, and about under 1 days a year stay below freezing all day.
How much rain does Saint-Thonan get?
About 1,147 mm a year, more than 93% of mainland French towns. December is the wettest month (147 mm) and June the driest (60 mm).
How sunny is it?
The nearest Météo-France station that records sunshine, Brest-Guipavas (5.1 km away), averages 1,555 hours of sunshine a year.
Are these figures for Saint-Thonan itself?
No: they are the normals of the Météo-France station matched to Saint-Thonan, Ploudaniel-Inrae, 2.8 km away. France publishes its climate normals by station, not by commune; a valley, a hill or the sea can make a difference over a few kilometers.
Where do these figures come from?
Météo-France’s fiches climatologiques: 30-year averages (1991–2020) for each of its long-running stations, published as open data since 2024. They are normals, not a forecast.
Source: Météo-France, fiches climatologiques, 1991–2020 statistics (station PLOUDANIEL-INRAE, edited 15/10/2026); altitude: IGN, RGE ALTI®. Licence Ouverte 2.0. Today’s forecast for Saint-Thonan →
Contains public sector information under the Licence Ouverte / Open Licence 2.0 (Etalab): INSEE, DGFiP, the Interior Ministry’s statistics service (SSMSI), the Ministry of Education (DEPP), the Health Ministry’s statistics service (DREES) and the Housing Ministry (Carte des loyers). Commune boundaries: IGN Admin Express.