Outside of mid-August to late October, when the weather is settled, Geneva's alpine climate can vary enormously. July brings hot weather, January very cold weather and September plentiful rain.
| Month | Temp (°C) | Rainfall (mm) | Humidity (%) | Sunshine (hours) |
| Jan | -2 - 4 | 63 | 2 | |
| Feb | -1 - 6 | 56 | 3 | |
| Mar | 2 - 10 | 55 | 5 | |
| Apr | 5 - 15 | 51 | 7 | |
| May | 9 - 19 | 68 | 8 | |
| Jun | 13 - 23 | 89 | 9 | |
| Jul | 15 - 25 | 64 | 10 | |
| Aug | 14 - 24 | 94 | 9 | |
| Sep | 12 - 21 | 99 | 7 | |
| Oct | 7 - 14 | 72 | 4 | |
| Nov | 3 - 8 | 83 | 2 | |
| Dec | 0 - 4 | 59 | 1 |