| Month | High | Low | Rain | Wet days | Score |
|---|---|---|---|---|---|
| January | -2.2° | -11.2° | 41.5mm | 9.2 | 12 |
| February | -0.1° | -9.2° | 42.6mm | 8 | 14 |
| March | 6.5° | -3.9° | 51.7mm | 7.7 | 33 |
| April | 13.5° | 2.2° | 91.6mm | 10.8 | 58 |
| May | 19.7° | 8° | 107.5mm | 12.7 | 74 |
| June | 25.3° | 13.6° | 123.6mm | 11.2 | 78 |
| July | 27.9° | 16.2° | 94.6mm | 8.6 | 79 |
| August | 26.8° | 15.5° | 105.8mm | 9.4 | 81 |
| September | 23.3° | 10.7° | 84.5mm | 8.2 | 84 |
| October | 16.1° | 4.4° | 70.5mm | 9.9 | 68 |
| November | 7.7° | -1.5° | 50.6mm | 7.9 | 40 |
| December | 0.4° | -8.2° | 47.6mm | 9.3 | 11 |
January in Waukesha averages a daily high of -2.2°C with nights around -11.2°C. Expect roughly 9.2 wet days totalling 41.5mm. A hard month to visit for comfort alone.
February in Waukesha averages a daily high of -0.1°C with nights around -9.2°C. Expect roughly 8 wet days totalling 42.6mm. A hard month to visit for comfort alone.
March in Waukesha averages a daily high of 6.5°C with nights around -3.9°C. Expect roughly 7.7 wet days totalling 51.7mm. A hard month to visit for comfort alone.
April in Waukesha averages a daily high of 13.5°C with nights around 2.2°C. Expect roughly 10.8 wet days totalling 91.6mm. Generally workable, with some weather to plan around.
May in Waukesha averages a daily high of 19.7°C with nights around 8°C. Expect roughly 12.7 wet days totalling 107.5mm. Generally workable, with some weather to plan around.
June in Waukesha averages a daily high of 25.3°C with nights around 13.6°C. Expect roughly 11.2 wet days totalling 123.6mm. Comfortable conditions for being outdoors all day.
July in Waukesha averages a daily high of 27.9°C with nights around 16.2°C. Expect roughly 8.6 wet days totalling 94.6mm. Comfortable conditions for being outdoors all day.
August in Waukesha averages a daily high of 26.8°C with nights around 15.5°C. Expect roughly 9.4 wet days totalling 105.8mm. Comfortable conditions for being outdoors all day.
September in Waukesha averages a daily high of 23.3°C with nights around 10.7°C. Expect roughly 8.2 wet days totalling 84.5mm. Comfortable conditions for being outdoors all day.
October in Waukesha averages a daily high of 16.1°C with nights around 4.4°C. Expect roughly 9.9 wet days totalling 70.5mm. Generally workable, with some weather to plan around.
November in Waukesha averages a daily high of 7.7°C with nights around -1.5°C. Expect roughly 7.9 wet days totalling 50.6mm. Demanding conditions — pack for it and plan indoor options.
December in Waukesha averages a daily high of 0.4°C with nights around -8.2°C. Expect roughly 9.3 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. Waukesha peaks at 84.
Based on 30 years of records, June–September scores highest for comfort in Waukesha, balancing daytime temperature against rainfall.
July is the warmest, averaging a daily high of 27.9°C.
June is the wettest, averaging 123.6mm of rain across roughly 11.2 wet days.
January is the coolest month, with average daily highs around -2.2°C.