Summer warmth: Saint-Lambert logs fewer 25-degree days than 79% of mainland French towns
Midwinter brings lows of about 1.9°C. Seasons differ by 23°C, from the coldest nights to the warmest afternoons. Its yearly rainfall falls short of 74% of mainland French towns. Plan for rain on about 117 days a year, the days with 1 mm or more.
Figures from Météo-France’s Trappes station, 4.7 km north.
A year in Saint-Lambert at a glance
Each month’s typical high and low in °C, at the Trappes station.
What a year in Saint-Lambert feels like
Typical highs and lows by season and by month, from Météo-France’s 1991–2020 normals at Trappes.
About 686 mm of rain a year
December is the wettest month and September the driest. About 18 days a year bring 10 mm or more. 7th wettest of 95 towns of 2,500+ in Yvelines.
Rain by month
Millimeters
Sunshine by month
Hours of sunshine at Trappes
39 frosts and 42 days of 25°C a year
On about 39 nights a year the air drops to 0°C or below, and on about 5 days it stays below freezing all day. About 42 days a year reach 25°C, and 9 reach 30°C.
Day counts are Météo-France’s 1991–2020 normals at Trappes: 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 Trappes
Trappes is 4.7 km north of Saint-Lambert. Every figure on this page is the station’s, not a measurement in Saint-Lambert itself.
| Station (Météo-France number) | Trappes (78621001) |
| Distance from the town | 4.7 km north |
| Station altitude | 167 m |
| Town altitude (its center) | 138 m |
| Period | 1991–2020 |
| Sunshine measured at | the same station |
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-Lambert 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 Yvelines.
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-Lambert | Trappes | 24.6°C | 1.9°C | 686 mm |
| Chevreuse 3.4 km | Choisel | 25.1°C 0.5°C warmer | 1.3°C 0.6°C colder | 709 mm |
| Voisins-le-Bretonneux 4.1 km | same station | 24.6°C about the same | 1.9°C about the same | 686 mm |
| Le Mesnil-Saint-Denis 4.6 km | same station | 24.6°C about the same | 1.9°C about the same | 686 mm |
| Saint-Rémy-lès-Chevreuse 5 km | Toussus-le-Noble | 25.2°C 0.6°C warmer | 1.6°C about the same | 677 mm |
| Montigny-le-Bretonneux 5 km | same station | 24.6°C about the same | 1.9°C about the same | 686 mm |
| La Verrière 5.1 km | same station | 24.6°C about the same | 1.9°C about the same | 686 mm |
Saint-Lambert weather by month
Average daily high and low, mean temperature and rain, 1991–2020, at the Trappes station.
| Month | High | Low | Mean | Rain | Sun (hours) |
|---|---|---|---|---|---|
| January | 6.8°C | 1.9°C | 4.3°C | 56 mm | 57 |
| February | 8.0°C | 1.8°C | 4.9°C | 50 mm | 81 |
| March | 11.9°C | 3.9°C | 7.9°C | 50 mm | 134 |
| April | 15.4°C | 6.0°C | 10.7°C | 50 mm | 176 |
| May | 18.8°C | 9.4°C | 14.1°C | 66 mm | 202 |
| June | 22.1°C | 12.5°C | 17.3°C | 57 mm | 210 |
| July | 24.6°C | 14.4°C | 19.5°C | 56 mm | 222 |
| August | 24.6°C | 14.2°C | 19.4°C | 56 mm | 216 |
| September | 20.7°C | 11.3°C | 16.0°C | 50 mm | 177 |
| October | 15.8°C | 8.5°C | 12.2°C | 62 mm | 117 |
| November | 10.4°C | 4.8°C | 7.6°C | 61 mm | 68 |
| December | 7.2°C | 2.4°C | 4.8°C | 72 mm | 55 |
| Year | 15.5°C | 7.6°C | 11.6°C | 686 mm | 1,714 |
Where Saint-Lambert’s numbers come from
Averages over 30 years, not a forecast.
- Temperature, rain and day counts: Météo-France’s fiche climatologique for Trappes, 4.7 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, Trappes, 4.7 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 Yvelines.
Météo-France fiches climatologiques · IGN RGE ALTI®. Licence Ouverte 2.0.
Questions about Saint-Lambert’s climate
How warm does Saint-Lambert get in summer?
July is the warmest month, with average highs of 24.6°C. About 42 days a year reach 25°C, fewer than 79% of mainland French towns, and about 9 reach 30°C.
How cold does Saint-Lambert get in winter?
February nights average 1.8°C. The air drops to 0°C or below on about 39 nights a year, and about 5 days a year stay below freezing all day.
How much rain does Saint-Lambert get?
About 686 mm a year, less than 74% of mainland French towns. December is the wettest month (72 mm) and September the driest (50 mm).
How sunny is it?
The nearest Météo-France station that records sunshine, Trappes (4.7 km away), averages 1,714 hours of sunshine a year.
Are these figures for Saint-Lambert itself?
No: they are the normals of the Météo-France station matched to Saint-Lambert, Trappes, 4.7 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 TRAPPES, edited 15/10/2026); altitude: IGN, RGE ALTI®. Licence Ouverte 2.0. Today’s forecast for Saint-Lambert →
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.