| Month | High | Low | Rain | Wet days | Score |
|---|---|---|---|---|---|
| January | 8° | 2.7° | 130.6mm | 18.3 | 32 |
| February | 9.9° | 2.8° | 88.4mm | 16.1 | 38 |
| March | 13.3° | 4.1° | 109.5mm | 18.3 | 49 |
| April | 16.3° | 5.8° | 85.5mm | 16.6 | 58 |
| May | 20.4° | 8.9° | 67.5mm | 13.3 | 73 |
| June | 23.7° | 11.7° | 55.3mm | 9.5 | 81 |
| July | 28.1° | 13.8° | 9.5mm | 3.3 | 89 |
| August | 28.3° | 13.8° | 14.7mm | 3.7 | 87 |
| September | 24.6° | 11.2° | 45.8mm | 6.9 | 86 |
| October | 17.9° | 8° | 98.4mm | 14.9 | 63 |
| November | 11.6° | 5.2° | 145.3mm | 18.4 | 43 |
| December | 7.7° | 2.7° | 147.1mm | 18.7 | 31 |
January in Gresham averages a daily high of 8°C with nights around 2.7°C. Expect roughly 18.3 wet days totalling 130.6mm. A hard month to visit for comfort alone.
February in Gresham averages a daily high of 9.9°C with nights around 2.8°C. Expect roughly 16.1 wet days totalling 88.4mm. Demanding conditions — pack for it and plan indoor options.
March in Gresham averages a daily high of 13.3°C with nights around 4.1°C. Expect roughly 18.3 wet days totalling 109.5mm. Demanding conditions — pack for it and plan indoor options.
April in Gresham averages a daily high of 16.3°C with nights around 5.8°C. Expect roughly 16.6 wet days totalling 85.5mm. Generally workable, with some weather to plan around.
May in Gresham averages a daily high of 20.4°C with nights around 8.9°C. Expect roughly 13.3 wet days totalling 67.5mm. Generally workable, with some weather to plan around.
June in Gresham averages a daily high of 23.7°C with nights around 11.7°C. Expect roughly 9.5 wet days totalling 55.3mm. Comfortable conditions for being outdoors all day.
July in Gresham averages a daily high of 28.1°C with nights around 13.8°C. Expect roughly 3.3 wet days totalling 9.5mm. Comfortable conditions for being outdoors all day.
August in Gresham averages a daily high of 28.3°C with nights around 13.8°C. Expect roughly 3.7 wet days totalling 14.7mm. Comfortable conditions for being outdoors all day.
September in Gresham averages a daily high of 24.6°C with nights around 11.2°C. Expect roughly 6.9 wet days totalling 45.8mm. Comfortable conditions for being outdoors all day.
October in Gresham averages a daily high of 17.9°C with nights around 8°C. Expect roughly 14.9 wet days totalling 98.4mm. Generally workable, with some weather to plan around.
November in Gresham averages a daily high of 11.6°C with nights around 5.2°C. Expect roughly 18.4 wet days totalling 145.3mm. Demanding conditions — pack for it and plan indoor options.
December in Gresham averages a daily high of 7.7°C with nights around 2.7°C. Expect roughly 18.7 wet days totalling 147.1mm. 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. Gresham peaks at 89.
Based on 30 years of records, June–September scores highest for comfort in Gresham, balancing daytime temperature against rainfall.
August is the warmest, averaging a daily high of 28.3°C.
December is the wettest, averaging 147.1mm of rain across roughly 18.7 wet days.
December is the coolest month, with average daily highs around 7.7°C.