May through September, with June–August as peak. May through September offers the warmest and sunniest conditions ideal for outdoor activities, Lake Zurich swimming, and seasonal events (Sechselauten in April, Street Parade in August, Zurich Film Festival in September). Shoulder months of May and September offer similar weather with fewer crowds. December draws visitors for Christmas markets but hotel rates spike due to proximity to Alpine ski resorts
| Month | High (°F) | Low (°F) | Notes |
|---|---|---|---|
| Jan | 40 | 29 | crisp & changeable |
| Feb | 43 | 29 | crisp & changeable |
| Mar | 50 | 33 | cool & changeable |
| Apr | 58 | 40 | cool & changeable |
| May | 64 | 47 | mild & wet |
| Jun | 72 | 55 | warm & wet |
| Jul | 75 | 59 | warm & changeable |
| Aug | 74 | 59 | warm & changeable |
| Sep | 67 | 53 | mild & changeable |
| Oct | 60 | 46 | cool & changeable |
| Nov | 48 | 37 | cool & changeable |
| Dec | 41 | 31 | crisp & changeable |