howmuchsun

Vitamin D from sunlight in France

How long you need in the sun to make vitamin D, and when the sun is too low to make any at all, for 5 cities in France.

CityLatitudeElevationVitamin D winter
Paris 48.85°N 42 m 3 Oct – 20 Mar (169 days)
Lille 50.63°N 20 m 27 Sep – 26 Mar (181 days)
Roubaix 50.69°N 33 m 27 Sep – 27 Mar (182 days)
Tourcoing 50.72°N 49 m 26 Sep – 27 Mar (183 days)
Dunkirk 51.03°N 8 m 25 Sep – 28 Mar (185 days)

How these dates are calculated