| Month | High | Low | Rain | Wet days | Score |
|---|---|---|---|---|---|
| January | -4.8° | -12.8° | 61.6mm | 14 | 2 |
| February | -2.9° | -12.3° | 52.2mm | 11.9 | 6 |
| March | 3.1° | -6.2° | 60.4mm | 10.8 | 12 |
| April | 11.5° | 1.4° | 79.5mm | 11.6 | 49 |
| May | 19.7° | 8.3° | 78.2mm | 12.6 | 74 |
| June | 24.5° | 13.7° | 97.8mm | 12.9 | 74 |
| July | 27° | 16° | 95.1mm | 11.6 | 77 |
| August | 25.9° | 14.9° | 89.1mm | 10.8 | 78 |
| September | 21.7° | 10.8° | 87.1mm | 10.5 | 79 |
| October | 13.8° | 4.8° | 91.9mm | 13.8 | 53 |
| November | 6° | -1.5° | 67.9mm | 12.6 | 25 |
| December | -1.2° | -8.1° | 76.9mm | 14.9 | 0 |
January in Nepean averages a daily high of -4.8°C with nights around -12.8°C. Expect roughly 14 wet days totalling 61.6mm. A hard month to visit for comfort alone.
February in Nepean averages a daily high of -2.9°C with nights around -12.3°C. Expect roughly 11.9 wet days totalling 52.2mm. A hard month to visit for comfort alone.
March in Nepean averages a daily high of 3.1°C with nights around -6.2°C. Expect roughly 10.8 wet days totalling 60.4mm. A hard month to visit for comfort alone.
April in Nepean averages a daily high of 11.5°C with nights around 1.4°C. Expect roughly 11.6 wet days totalling 79.5mm. Demanding conditions — pack for it and plan indoor options.
May in Nepean averages a daily high of 19.7°C with nights around 8.3°C. Expect roughly 12.6 wet days totalling 78.2mm. Generally workable, with some weather to plan around.
June in Nepean averages a daily high of 24.5°C with nights around 13.7°C. Expect roughly 12.9 wet days totalling 97.8mm. Generally workable, with some weather to plan around.
July in Nepean averages a daily high of 27°C with nights around 16°C. Expect roughly 11.6 wet days totalling 95.1mm. Comfortable conditions for being outdoors all day.
August in Nepean averages a daily high of 25.9°C with nights around 14.9°C. Expect roughly 10.8 wet days totalling 89.1mm. Comfortable conditions for being outdoors all day.
September in Nepean averages a daily high of 21.7°C with nights around 10.8°C. Expect roughly 10.5 wet days totalling 87.1mm. Comfortable conditions for being outdoors all day.
October in Nepean averages a daily high of 13.8°C with nights around 4.8°C. Expect roughly 13.8 wet days totalling 91.9mm. Demanding conditions — pack for it and plan indoor options.
November in Nepean averages a daily high of 6°C with nights around -1.5°C. Expect roughly 12.6 wet days totalling 67.9mm. A hard month to visit for comfort alone.
December in Nepean averages a daily high of -1.2°C with nights around -8.1°C. Expect roughly 14.9 wet days totalling 76.9mm. 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. Nepean peaks at 79.
Based on 30 years of records, May–September scores highest for comfort in Nepean, balancing daytime temperature against rainfall.
July is the warmest, averaging a daily high of 27°C.
June is the wettest, averaging 97.8mm of rain across roughly 12.9 wet days.
January is the coolest month, with average daily highs around -4.8°C.