| Month | High | Low | Rain | Wet days | Score |
|---|---|---|---|---|---|
| January | 3.3° | -8.3° | 13.2mm | 5 | 22 |
| February | 3.2° | -8.6° | 14.4mm | 4.9 | 21 |
| March | 9.2° | -4.1° | 26.5mm | 5 | 46 |
| April | 13.6° | -0.6° | 38.6mm | 7.4 | 61 |
| May | 19.1° | 4.7° | 63.2mm | 9.3 | 79 |
| June | 26.8° | 10.3° | 33.2mm | 6.7 | 87 |
| July | 31.8° | 14.3° | 30.7mm | 6 | 69 |
| August | 30° | 12.9° | 26.7mm | 5.9 | 76 |
| September | 25° | 7.3° | 27.7mm | 5.9 | 88 |
| October | 16.1° | 1.2° | 33.4mm | 5.2 | 76 |
| November | 9.1° | -3.4° | 11.5mm | 4.2 | 49 |
| December | 3.5° | -7.6° | 17.7mm | 4.5 | 24 |
January in Casper averages a daily high of 3.3°C with nights around -8.3°C. Expect roughly 5 wet days totalling 13.2mm. A hard month to visit for comfort alone.
February in Casper averages a daily high of 3.2°C with nights around -8.6°C. Expect roughly 4.9 wet days totalling 14.4mm. A hard month to visit for comfort alone.
March in Casper averages a daily high of 9.2°C with nights around -4.1°C. Expect roughly 5 wet days totalling 26.5mm. Demanding conditions — pack for it and plan indoor options.
April in Casper averages a daily high of 13.6°C with nights around -0.6°C. Expect roughly 7.4 wet days totalling 38.6mm. Generally workable, with some weather to plan around.
May in Casper averages a daily high of 19.1°C with nights around 4.7°C. Expect roughly 9.3 wet days totalling 63.2mm. Comfortable conditions for being outdoors all day.
June in Casper averages a daily high of 26.8°C with nights around 10.3°C. Expect roughly 6.7 wet days totalling 33.2mm. Comfortable conditions for being outdoors all day.
July in Casper averages a daily high of 31.8°C with nights around 14.3°C. Expect roughly 6 wet days totalling 30.7mm. Generally workable, with some weather to plan around.
August in Casper averages a daily high of 30°C with nights around 12.9°C. Expect roughly 5.9 wet days totalling 26.7mm. Comfortable conditions for being outdoors all day.
September in Casper averages a daily high of 25°C with nights around 7.3°C. Expect roughly 5.9 wet days totalling 27.7mm. Comfortable conditions for being outdoors all day.
October in Casper averages a daily high of 16.1°C with nights around 1.2°C. Expect roughly 5.2 wet days totalling 33.4mm. Comfortable conditions for being outdoors all day.
November in Casper averages a daily high of 9.1°C with nights around -3.4°C. Expect roughly 4.2 wet days totalling 11.5mm. Demanding conditions — pack for it and plan indoor options.
December in Casper averages a daily high of 3.5°C with nights around -7.6°C. Expect roughly 4.5 wet days totalling 17.7mm. 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. Casper peaks at 88.
Based on 30 years of records, June scores highest for comfort in Casper, balancing daytime temperature against rainfall.
July is the warmest, averaging a daily high of 31.8°C.
May is the wettest, averaging 63.2mm of rain across roughly 9.3 wet days.
February is the coolest month, with average daily highs around 3.2°C.