Iceland has no ideal window. No month clears the bar for comfortable travel outright, but May–Jul comes closest — rated fair rather than too hot, too cold or too wet.
Cold; brief mild summer
| Month | High °C | High °F | Rainy days | Verdict |
|---|---|---|---|---|
| January | 1.6 | 35 | 72% | Too cold |
| February | 1.7 | 35 | 69% | Too cold |
| March | 2.3 | 36 | 65% | Too cold |
| April | 4.8 | 41 | 59% | Too cold |
| May | 8.1 | 47 | 51% | Fair |
| June | 11.4 | 53 | 51% | Fair |
| July | 13.3 | 56 | 52% | Fair |
| August | 12.6 | 55 | 58% | Too wet |
| September | 9.7 | 49 | 69% | Too wet |
| October | 5.8 | 42 | 59% | Too wet |
| November | 3.1 | 38 | 66% | Too cold |
| December | 1.8 | 35 | 69% | 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.
May is the driest month, with rain on 51% of days and daytime highs near 8.1°C (47°F). January is the wettest, at 72%. The warmest month is July at 13.3°C (56°F); the coolest is January at 1.6°C (35°F). The record rules out too cold in Nov–Apr; too wet in Aug–Oct.