| Month | High | Low | Rain | Wet days | Score |
|---|---|---|---|---|---|
| January | -4.2° | -13.4° | 66.5mm | 14.3 | 1 |
| February | -2.8° | -12.8° | 59.9mm | 12.6 | 5 |
| March | 2.8° | -6.5° | 68.4mm | 13.5 | 5 |
| April | 11.3° | 0.9° | 89.8mm | 12.9 | 45 |
| May | 19.6° | 7.8° | 79.3mm | 13 | 73 |
| June | 24.4° | 13.3° | 89.2mm | 12.2 | 76 |
| July | 26.5° | 15.5° | 108mm | 11.4 | 77 |
| August | 25.4° | 14.1° | 93.6mm | 10.2 | 80 |
| September | 21.5° | 9.9° | 83.8mm | 10.6 | 79 |
| October | 13.9° | 4.3° | 104.6mm | 12.5 | 55 |
| November | 6.1° | -1.8° | 72.9mm | 12.4 | 25 |
| December | -0.5° | -8.3° | 87.5mm | 15.2 | 0 |
January in Saint-Jean-sur-Richelieu averages a daily high of -4.2°C with nights around -13.4°C. Expect roughly 14.3 wet days totalling 66.5mm. A hard month to visit for comfort alone.
February in Saint-Jean-sur-Richelieu averages a daily high of -2.8°C with nights around -12.8°C. Expect roughly 12.6 wet days totalling 59.9mm. A hard month to visit for comfort alone.
March in Saint-Jean-sur-Richelieu averages a daily high of 2.8°C with nights around -6.5°C. Expect roughly 13.5 wet days totalling 68.4mm. A hard month to visit for comfort alone.
April in Saint-Jean-sur-Richelieu averages a daily high of 11.3°C with nights around 0.9°C. Expect roughly 12.9 wet days totalling 89.8mm. Demanding conditions — pack for it and plan indoor options.
May in Saint-Jean-sur-Richelieu averages a daily high of 19.6°C with nights around 7.8°C. Expect roughly 13 wet days totalling 79.3mm. Generally workable, with some weather to plan around.
June in Saint-Jean-sur-Richelieu averages a daily high of 24.4°C with nights around 13.3°C. Expect roughly 12.2 wet days totalling 89.2mm. Comfortable conditions for being outdoors all day.
July in Saint-Jean-sur-Richelieu averages a daily high of 26.5°C with nights around 15.5°C. Expect roughly 11.4 wet days totalling 108mm. Comfortable conditions for being outdoors all day.
August in Saint-Jean-sur-Richelieu averages a daily high of 25.4°C with nights around 14.1°C. Expect roughly 10.2 wet days totalling 93.6mm. Comfortable conditions for being outdoors all day.
September in Saint-Jean-sur-Richelieu averages a daily high of 21.5°C with nights around 9.9°C. Expect roughly 10.6 wet days totalling 83.8mm. Comfortable conditions for being outdoors all day.
October in Saint-Jean-sur-Richelieu averages a daily high of 13.9°C with nights around 4.3°C. Expect roughly 12.5 wet days totalling 104.6mm. Generally workable, with some weather to plan around.
November in Saint-Jean-sur-Richelieu averages a daily high of 6.1°C with nights around -1.8°C. Expect roughly 12.4 wet days totalling 72.9mm. A hard month to visit for comfort alone.
December in Saint-Jean-sur-Richelieu averages a daily high of -0.5°C with nights around -8.3°C. Expect roughly 15.2 wet days totalling 87.5mm. 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. Saint-Jean-sur-Richelieu peaks at 80.
Based on 30 years of records, May–September scores highest for comfort in Saint-Jean-sur-Richelieu, balancing daytime temperature against rainfall.
July is the warmest, averaging a daily high of 26.5°C.
July is the wettest, averaging 108mm of rain across roughly 11.4 wet days.
January is the coolest month, with average daily highs around -4.2°C.