Czechia has two good windows: May and Aug–Sep. They sit either side of the season the climate record rules out, which is why the shoulder months matter here. The recommended window is May–Sep.
Cold winters, warm summers
| Month | High °C | High °F | Rainy days | Verdict |
|---|---|---|---|---|
| January | 1.2 | 34 | 34% | Too cold |
| February | 3.4 | 38 | 31% | Too cold |
| March | 8.2 | 47 | 33% | Fair |
| April | 14.1 | 57 | 30% | Fair |
| May | 18.9 | 66 | 43% | Go |
| June | 22.8 | 73 | 46% | Fair |
| July | 25.2 | 77 | 47% | Fair |
| August | 25.3 | 78 | 37% | Go |
| September | 20.2 | 68 | 33% | Go |
| October | 14.0 | 57 | 30% | Fair |
| November | 6.9 | 44 | 30% | Fair |
| December | 2.1 | 36 | 34% | Too cold |
Verdict combines mean daytime high with rainy-day frequency. “Rainy days” is the share of days in the month with at least 1 mm of rain.
April is the driest month, with rain on 30% of days and daytime highs near 14.1°C (57°F). July is the wettest, at 47%. Temperature swings hard across the year — 24.1°C between August (25.3°C / 78°F) and January (1.2°C / 34°F) — so packing for the wrong month is the main risk. The record rules out too cold in Dec–Feb.