| Month | High | Low | Rain | Wet days | Score |
|---|---|---|---|---|---|
| January | 7.7° | -8° | 15.4mm | 4.8 | 36 |
| February | 8.3° | -7.2° | 19.8mm | 5.3 | 38 |
| March | 12.2° | -3.3° | 37.7mm | 5 | 57 |
| April | 15.4° | 0.2° | 50.8mm | 6.2 | 70 |
| May | 20.3° | 5° | 58.1mm | 8.7 | 83 |
| June | 27.1° | 10.4° | 55.6mm | 7.7 | 84 |
| July | 30.4° | 13.6° | 63.1mm | 8.7 | 69 |
| August | 28.9° | 12.6° | 63.1mm | 10 | 72 |
| September | 25.5° | 8.4° | 35.3mm | 6.1 | 88 |
| October | 18.7° | 1.7° | 21.7mm | 4.3 | 87 |
| November | 13.1° | -3.3° | 16.7mm | 4.1 | 62 |
| December | 8.2° | -7.7° | 16.6mm | 4.7 | 38 |
January in Castle Rock averages a daily high of 7.7°C with nights around -8°C. Expect roughly 4.8 wet days totalling 15.4mm. Demanding conditions — pack for it and plan indoor options.
February in Castle Rock averages a daily high of 8.3°C with nights around -7.2°C. Expect roughly 5.3 wet days totalling 19.8mm. Demanding conditions — pack for it and plan indoor options.
March in Castle Rock averages a daily high of 12.2°C with nights around -3.3°C. Expect roughly 5 wet days totalling 37.7mm. Generally workable, with some weather to plan around.
April in Castle Rock averages a daily high of 15.4°C with nights around 0.2°C. Expect roughly 6.2 wet days totalling 50.8mm. Generally workable, with some weather to plan around.
May in Castle Rock averages a daily high of 20.3°C with nights around 5°C. Expect roughly 8.7 wet days totalling 58.1mm. Comfortable conditions for being outdoors all day.
June in Castle Rock averages a daily high of 27.1°C with nights around 10.4°C. Expect roughly 7.7 wet days totalling 55.6mm. Comfortable conditions for being outdoors all day.
July in Castle Rock averages a daily high of 30.4°C with nights around 13.6°C. Expect roughly 8.7 wet days totalling 63.1mm. Generally workable, with some weather to plan around.
August in Castle Rock averages a daily high of 28.9°C with nights around 12.6°C. Expect roughly 10 wet days totalling 63.1mm. Generally workable, with some weather to plan around.
September in Castle Rock averages a daily high of 25.5°C with nights around 8.4°C. Expect roughly 6.1 wet days totalling 35.3mm. Comfortable conditions for being outdoors all day.
October in Castle Rock averages a daily high of 18.7°C with nights around 1.7°C. Expect roughly 4.3 wet days totalling 21.7mm. Comfortable conditions for being outdoors all day.
November in Castle Rock averages a daily high of 13.1°C with nights around -3.3°C. Expect roughly 4.1 wet days totalling 16.7mm. Generally workable, with some weather to plan around.
December in Castle Rock averages a daily high of 8.2°C with nights around -7.7°C. Expect roughly 4.7 wet days totalling 16.6mm. Demanding conditions — pack for it and plan indoor options.
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. Castle Rock peaks at 88.
Based on 30 years of records, May–June scores highest for comfort in Castle Rock, balancing daytime temperature against rainfall.
July is the warmest, averaging a daily high of 30.4°C.
July is the wettest, averaging 63.1mm of rain across roughly 8.7 wet days.
January is the coolest month, with average daily highs around 7.7°C.