| Month | High | Low | Rain | Wet days | Score |
|---|---|---|---|---|---|
| January | -0.7° | -8.9° | 76.2mm | 11.5 | 7 |
| February | 0.8° | -9.5° | 54.2mm | 8.6 | 13 |
| March | 5.5° | -5.8° | 57.3mm | 8.9 | 24 |
| April | 11.9° | -0.4° | 72mm | 11.4 | 48 |
| May | 19.5° | 5.5° | 71.6mm | 10.2 | 78 |
| June | 25° | 11.1° | 78.4mm | 10.4 | 79 |
| July | 27.3° | 13.5° | 64.3mm | 9.5 | 80 |
| August | 26.8° | 12.8° | 71.5mm | 9.5 | 81 |
| September | 22.9° | 9° | 69.3mm | 9.9 | 80 |
| October | 15.1° | 3.5° | 68.3mm | 12.2 | 60 |
| November | 7.9° | -1.5° | 68.3mm | 10.9 | 34 |
| December | 2.3° | -5.6° | 57.3mm | 11.6 | 10 |
January in Halton Hills averages a daily high of -0.7°C with nights around -8.9°C. Expect roughly 11.5 wet days totalling 76.2mm. A hard month to visit for comfort alone.
February in Halton Hills averages a daily high of 0.8°C with nights around -9.5°C. Expect roughly 8.6 wet days totalling 54.2mm. A hard month to visit for comfort alone.
March in Halton Hills averages a daily high of 5.5°C with nights around -5.8°C. Expect roughly 8.9 wet days totalling 57.3mm. A hard month to visit for comfort alone.
April in Halton Hills averages a daily high of 11.9°C with nights around -0.4°C. Expect roughly 11.4 wet days totalling 72mm. Demanding conditions — pack for it and plan indoor options.
May in Halton Hills averages a daily high of 19.5°C with nights around 5.5°C. Expect roughly 10.2 wet days totalling 71.6mm. Comfortable conditions for being outdoors all day.
June in Halton Hills averages a daily high of 25°C with nights around 11.1°C. Expect roughly 10.4 wet days totalling 78.4mm. Comfortable conditions for being outdoors all day.
July in Halton Hills averages a daily high of 27.3°C with nights around 13.5°C. Expect roughly 9.5 wet days totalling 64.3mm. Comfortable conditions for being outdoors all day.
August in Halton Hills averages a daily high of 26.8°C with nights around 12.8°C. Expect roughly 9.5 wet days totalling 71.5mm. Comfortable conditions for being outdoors all day.
September in Halton Hills averages a daily high of 22.9°C with nights around 9°C. Expect roughly 9.9 wet days totalling 69.3mm. Comfortable conditions for being outdoors all day.
October in Halton Hills averages a daily high of 15.1°C with nights around 3.5°C. Expect roughly 12.2 wet days totalling 68.3mm. Generally workable, with some weather to plan around.
November in Halton Hills averages a daily high of 7.9°C with nights around -1.5°C. Expect roughly 10.9 wet days totalling 68.3mm. A hard month to visit for comfort alone.
December in Halton Hills averages a daily high of 2.3°C with nights around -5.6°C. Expect roughly 11.6 wet days totalling 57.3mm. 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. Halton Hills peaks at 81.
Based on 30 years of records, May–September scores highest for comfort in Halton Hills, balancing daytime temperature against rainfall.
July is the warmest, averaging a daily high of 27.3°C.
June is the wettest, averaging 78.4mm of rain across roughly 10.4 wet days.
January is the coolest month, with average daily highs around -0.7°C.