| Month | High | Low | Rain | Wet days | Score |
|---|---|---|---|---|---|
| January | -2° | -10.9° | 43.1mm | 10.3 | 9 |
| February | 0.4° | -9.8° | 41.4mm | 8.6 | 13 |
| March | 7.3° | -3.7° | 55.2mm | 9.5 | 32 |
| April | 14.5° | 2.1° | 89.3mm | 12.3 | 58 |
| May | 21.1° | 8.9° | 104.9mm | 13.1 | 74 |
| June | 26.7° | 14.5° | 124.1mm | 12.5 | 75 |
| July | 28.7° | 16.5° | 114.1mm | 10.1 | 73 |
| August | 27.9° | 15.5° | 106.9mm | 10 | 76 |
| September | 24.4° | 10.7° | 88.7mm | 9.3 | 81 |
| October | 16.8° | 4.4° | 80.3mm | 10.3 | 69 |
| November | 8.3° | -1.9° | 54.5mm | 8.5 | 40 |
| December | 1.1° | -7.4° | 47.6mm | 9.7 | 12 |
January in Janesville averages a daily high of -2°C with nights around -10.9°C. Expect roughly 10.3 wet days totalling 43.1mm. A hard month to visit for comfort alone.
February in Janesville averages a daily high of 0.4°C with nights around -9.8°C. Expect roughly 8.6 wet days totalling 41.4mm. A hard month to visit for comfort alone.
March in Janesville averages a daily high of 7.3°C with nights around -3.7°C. Expect roughly 9.5 wet days totalling 55.2mm. A hard month to visit for comfort alone.
April in Janesville averages a daily high of 14.5°C with nights around 2.1°C. Expect roughly 12.3 wet days totalling 89.3mm. Generally workable, with some weather to plan around.
May in Janesville averages a daily high of 21.1°C with nights around 8.9°C. Expect roughly 13.1 wet days totalling 104.9mm. Generally workable, with some weather to plan around.
June in Janesville averages a daily high of 26.7°C with nights around 14.5°C. Expect roughly 12.5 wet days totalling 124.1mm. Comfortable conditions for being outdoors all day.
July in Janesville averages a daily high of 28.7°C with nights around 16.5°C. Expect roughly 10.1 wet days totalling 114.1mm. Generally workable, with some weather to plan around.
August in Janesville averages a daily high of 27.9°C with nights around 15.5°C. Expect roughly 10 wet days totalling 106.9mm. Comfortable conditions for being outdoors all day.
September in Janesville averages a daily high of 24.4°C with nights around 10.7°C. Expect roughly 9.3 wet days totalling 88.7mm. Comfortable conditions for being outdoors all day.
October in Janesville averages a daily high of 16.8°C with nights around 4.4°C. Expect roughly 10.3 wet days totalling 80.3mm. Generally workable, with some weather to plan around.
November in Janesville averages a daily high of 8.3°C with nights around -1.9°C. Expect roughly 8.5 wet days totalling 54.5mm. Demanding conditions — pack for it and plan indoor options.
December in Janesville averages a daily high of 1.1°C with nights around -7.4°C. Expect roughly 9.7 wet days totalling 47.6mm. 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. Janesville peaks at 81.
Based on 30 years of records, May–September scores highest for comfort in Janesville, balancing daytime temperature against rainfall.
July is the warmest, averaging a daily high of 28.7°C.
June is the wettest, averaging 124.1mm of rain across roughly 12.5 wet days.
January is the coolest month, with average daily highs around -2°C.