Frost comes to Sy more often than to 93% of mainland French towns
The warmest part of a July day comes in at 25.1°C on average. Rain peaks in December and eases off in April. None of the 13 towns of 2,500+ in Ardennes gets more rain. Keep the boiler serviced for the months from November to April, which average under 10°C.
These are the figures of Météo-France’s Linay station, 27 km north-east; at that distance they describe the area more than the town.
A year in Sy at a glance
Each month’s typical high and low in °C, at the Linay station.
What a year in Sy feels like
Typical highs and lows by season and by month, from Météo-France’s 1991–2020 normals at Linay.
About 969 mm of rain a year
December is the wettest month and April the driest. About 31 days a year bring 10 mm or more. The wettest of 13 towns of 2,500+ in Ardennes.
Rain by month
Millimeters
Sunshine by month
Hours of sunshine at Charleville-Mez
A frosty town: 74 frosts and 51 days of 25°C a year
On about 74 nights a year the air drops to 0°C or below, and on about 7 days it stays below freezing all day. About 51 days a year reach 25°C, and 14 reach 30°C.
Day counts are Météo-France’s 1991–2020 normals at Linay: 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 Linay
Linay is 27 km north-east of Sy. Every figure on this page is the station’s, not a measurement in Sy itself.
| Station (Météo-France number) | Linay (08255001) |
| Distance from the town | 27 km north-east |
| Station altitude | 177 m |
| Town altitude (its center) | 181 m |
| Period | 1991–2020 |
| Nearest station of any kind | 12 km |
| Sunshine measured at | Charleville-Mez, 34 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 Sy 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 Ardennes.
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 |
|---|---|---|---|---|
| Sy | Linay | 25.1°C | −0.4°C | 969 mm |
| Vouziers 18 km | Cauroy | 25.3°C about the same | 0.3°C 0.7°C milder | 750 mm |
| Sedan 21 km | Charleville-Mez | 24.1°C 1°C cooler | −0.3°C about the same | 928 mm |
| Vivier-au-Court 25 km | Charleville-Mez | 24.1°C 1°C cooler | −0.3°C about the same | 928 mm |
| Vrigne aux Bois 25 km | Charleville-Mez | 24.1°C 1°C cooler | −0.3°C about the same | 928 mm |
| Carignan 25 km | same station | 25.1°C about the same | −0.4°C about the same | 969 mm |
| Villers-Semeuse 27 km | Charleville-Mez | 24.1°C 1°C cooler | −0.3°C about the same | 928 mm |
Sy weather by month
Average daily high and low, mean temperature and rain, 1991–2020, at the Linay station; sunshine at Charleville-Mez.
| Month | High | Low | Mean | Rain | Sun (hours) |
|---|---|---|---|---|---|
| January | 5.6°C | −0.4°C | 2.6°C | 104 mm | 50 |
| February | 7.2°C | −0.4°C | 3.4°C | 82 mm | 69 |
| March | 11.7°C | 1.5°C | 6.6°C | 71 mm | 128 |
| April | 16.0°C | 3.3°C | 9.6°C | 58 mm | 177 |
| May | 20.0°C | 7.4°C | 13.7°C | 71 mm | 197 |
| June | 23.0°C | 10.6°C | 16.8°C | 75 mm | 203 |
| July | 25.1°C | 12.3°C | 18.7°C | 74 mm | 214 |
| August | 24.7°C | 11.9°C | 18.3°C | 81 mm | 199 |
| September | 20.7°C | 8.7°C | 14.7°C | 64 mm | 153 |
| October | 15.4°C | 6.3°C | 10.9°C | 82 mm | 97 |
| November | 9.5°C | 3.2°C | 6.3°C | 88 mm | 48 |
| December | 6.3°C | 0.7°C | 3.5°C | 120 mm | 41 |
| Year | 15.4°C | 5.4°C | 10.4°C | 969 mm | 1,576 |
Where Sy’s numbers come from
Averages over 30 years, not a forecast.
- Temperature, rain and day counts: Météo-France’s fiche climatologique for Linay, 27 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, Charleville-Mez, 34 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 Ardennes.
Météo-France fiches climatologiques · IGN RGE ALTI®. Licence Ouverte 2.0.
Questions about Sy’s climate
How warm does Sy get in summer?
July is the warmest month, with average highs of 25.1°C. About 51 days a year reach 25°C, fewer than 66% of mainland French towns, and about 14 reach 30°C.
How cold does Sy get in winter?
January nights average −0.4°C. The air drops to 0°C or below on about 74 nights a year, and about 7 days a year stay below freezing all day.
How much rain does Sy get?
About 969 mm a year, more than 86% of mainland French towns. December is the wettest month (120 mm) and April the driest (58 mm).
How sunny is it?
The nearest Météo-France station that records sunshine, Charleville-Mez (34 km away), averages 1,576 hours of sunshine a year.
Are these figures for Sy itself?
No: they are the normals of the Météo-France station matched to Sy, Linay, 27 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 LINAY, edited 15/10/2026); altitude: IGN, RGE ALTI®. Licence Ouverte 2.0. Today’s forecast for Sy →
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.