| Month | High | Low | Rain | Wet days | Score |
|---|---|---|---|---|---|
| January | -0.6° | -8.9° | 31.2mm | 8.4 | 13 |
| February | 1.9° | -7.7° | 32.5mm | 7 | 16 |
| March | 8.7° | -2.2° | 51.1mm | 9.7 | 38 |
| April | 15.6° | 3.2° | 86.9mm | 11.7 | 63 |
| May | 21.8° | 9.3° | 109.6mm | 13.1 | 74 |
| June | 27° | 14.7° | 94mm | 11.3 | 77 |
| July | 28.9° | 17.1° | 96.2mm | 10.2 | 72 |
| August | 27.9° | 16.2° | 83mm | 10.6 | 75 |
| September | 24.7° | 12° | 74.5mm | 9.5 | 81 |
| October | 17.2° | 5.5° | 78.6mm | 10.8 | 69 |
| November | 9.3° | -0.6° | 47.9mm | 8.3 | 45 |
| December | 2.3° | -6° | 42.6mm | 8.8 | 15 |
January in Wheaton averages a daily high of -0.6°C with nights around -8.9°C. Expect roughly 8.4 wet days totalling 31.2mm. A hard month to visit for comfort alone.
February in Wheaton averages a daily high of 1.9°C with nights around -7.7°C. Expect roughly 7 wet days totalling 32.5mm. A hard month to visit for comfort alone.
March in Wheaton averages a daily high of 8.7°C with nights around -2.2°C. Expect roughly 9.7 wet days totalling 51.1mm. Demanding conditions — pack for it and plan indoor options.
April in Wheaton averages a daily high of 15.6°C with nights around 3.2°C. Expect roughly 11.7 wet days totalling 86.9mm. Generally workable, with some weather to plan around.
May in Wheaton averages a daily high of 21.8°C with nights around 9.3°C. Expect roughly 13.1 wet days totalling 109.6mm. Generally workable, with some weather to plan around.
June in Wheaton averages a daily high of 27°C with nights around 14.7°C. Expect roughly 11.3 wet days totalling 94mm. Comfortable conditions for being outdoors all day.
July in Wheaton averages a daily high of 28.9°C with nights around 17.1°C. Expect roughly 10.2 wet days totalling 96.2mm. Generally workable, with some weather to plan around.
August in Wheaton averages a daily high of 27.9°C with nights around 16.2°C. Expect roughly 10.6 wet days totalling 83mm. Comfortable conditions for being outdoors all day.
September in Wheaton averages a daily high of 24.7°C with nights around 12°C. Expect roughly 9.5 wet days totalling 74.5mm. Comfortable conditions for being outdoors all day.
October in Wheaton averages a daily high of 17.2°C with nights around 5.5°C. Expect roughly 10.8 wet days totalling 78.6mm. Generally workable, with some weather to plan around.
November in Wheaton averages a daily high of 9.3°C with nights around -0.6°C. Expect roughly 8.3 wet days totalling 47.9mm. Demanding conditions — pack for it and plan indoor options.
December in Wheaton averages a daily high of 2.3°C with nights around -6°C. Expect roughly 8.8 wet days totalling 42.6mm. A hard month to visit for comfort alone.
Each month scores out of 100. It starts at 100 and loses points for daytime highs outside a 20–27°C band, for wet days, and for nights below 2°C. Nothing else is weighted in — no crowd data, no prices, no opinion. Wheaton peaks at 81.
Based on 30 years of records, May–June scores highest for comfort in Wheaton, balancing daytime temperature against rainfall.
July is the warmest, averaging a daily high of 28.9°C.
May is the wettest, averaging 109.6mm of rain across roughly 13.1 wet days.
January is the coolest month, with average daily highs around -0.6°C.