| Month | High | Low | Rain | Wet days | Score |
|---|---|---|---|---|---|
| January | 0° | -7.6° | 32.2mm | 6.7 | 17 |
| February | 2.3° | -6.4° | 32.4mm | 6.1 | 20 |
| March | 8.4° | -1.2° | 48.8mm | 9 | 40 |
| April | 14.7° | 3.8° | 78.9mm | 11.3 | 60 |
| May | 20.9° | 9.6° | 98.4mm | 12 | 76 |
| June | 26.6° | 15.4° | 101.7mm | 10.3 | 79 |
| July | 28.8° | 18.3° | 87.6mm | 9 | 75 |
| August | 27.8° | 17.7° | 82.4mm | 8.9 | 79 |
| September | 24.3° | 13.5° | 72.5mm | 9.2 | 82 |
| October | 17.1° | 6.8° | 79.3mm | 10.8 | 69 |
| November | 9.5° | 0.5° | 46.2mm | 8.8 | 47 |
| December | 2.9° | -4.7° | 44.5mm | 8.1 | 19 |
January in Evanston averages a daily high of 0°C with nights around -7.6°C. Expect roughly 6.7 wet days totalling 32.2mm. A hard month to visit for comfort alone.
February in Evanston averages a daily high of 2.3°C with nights around -6.4°C. Expect roughly 6.1 wet days totalling 32.4mm. A hard month to visit for comfort alone.
March in Evanston averages a daily high of 8.4°C with nights around -1.2°C. Expect roughly 9 wet days totalling 48.8mm. Demanding conditions — pack for it and plan indoor options.
April in Evanston averages a daily high of 14.7°C with nights around 3.8°C. Expect roughly 11.3 wet days totalling 78.9mm. Generally workable, with some weather to plan around.
May in Evanston averages a daily high of 20.9°C with nights around 9.6°C. Expect roughly 12 wet days totalling 98.4mm. Comfortable conditions for being outdoors all day.
June in Evanston averages a daily high of 26.6°C with nights around 15.4°C. Expect roughly 10.3 wet days totalling 101.7mm. Comfortable conditions for being outdoors all day.
July in Evanston averages a daily high of 28.8°C with nights around 18.3°C. Expect roughly 9 wet days totalling 87.6mm. Comfortable conditions for being outdoors all day.
August in Evanston averages a daily high of 27.8°C with nights around 17.7°C. Expect roughly 8.9 wet days totalling 82.4mm. Comfortable conditions for being outdoors all day.
September in Evanston averages a daily high of 24.3°C with nights around 13.5°C. Expect roughly 9.2 wet days totalling 72.5mm. Comfortable conditions for being outdoors all day.
October in Evanston averages a daily high of 17.1°C with nights around 6.8°C. Expect roughly 10.8 wet days totalling 79.3mm. Generally workable, with some weather to plan around.
November in Evanston averages a daily high of 9.5°C with nights around 0.5°C. Expect roughly 8.8 wet days totalling 46.2mm. Demanding conditions — pack for it and plan indoor options.
December in Evanston averages a daily high of 2.9°C with nights around -4.7°C. Expect roughly 8.1 wet days totalling 44.5mm. 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. Evanston peaks at 82.
Based on 30 years of records, May–September scores highest for comfort in Evanston, balancing daytime temperature against rainfall.
July is the warmest, averaging a daily high of 28.8°C.
June is the wettest, averaging 101.7mm of rain across roughly 10.3 wet days.
January is the coolest month, with average daily highs around 0°C.