| Month | High | Low | Rain | Wet days | Score |
|---|---|---|---|---|---|
| January | 21.2° | 9.1° | 68.4mm | 6.2 | 88 |
| February | 21.3° | 9.3° | 72.3mm | 6.3 | 87 |
| March | 22.4° | 10.7° | 39.8mm | 4.9 | 90 |
| April | 23.5° | 12° | 19.9mm | 2.8 | 94 |
| May | 24.2° | 14.2° | 7.9mm | 1.9 | 96 |
| June | 26.1° | 16° | 0.9mm | 0.6 | 99 |
| July | 29° | 18° | 0.7mm | 0.4 | 91 |
| August | 30° | 18.4° | 1.7mm | 0.2 | 88 |
| September | 29.5° | 17.6° | 3.5mm | 0.7 | 89 |
| October | 27.1° | 15° | 12.9mm | 1.8 | 96 |
| November | 24° | 11.4° | 21mm | 2.9 | 94 |
| December | 20.8° | 8.8° | 60mm | 6 | 88 |
January in Tustin averages a daily high of 21.2°C with nights around 9.1°C. Expect roughly 6.2 wet days totalling 68.4mm. Comfortable conditions for being outdoors all day.
February in Tustin averages a daily high of 21.3°C with nights around 9.3°C. Expect roughly 6.3 wet days totalling 72.3mm. Comfortable conditions for being outdoors all day.
March in Tustin averages a daily high of 22.4°C with nights around 10.7°C. Expect roughly 4.9 wet days totalling 39.8mm. Comfortable conditions for being outdoors all day.
April in Tustin averages a daily high of 23.5°C with nights around 12°C. Rain is rare — about 2.8 wet days and 19.9mm across the month. Comfortable conditions for being outdoors all day.
May in Tustin averages a daily high of 24.2°C with nights around 14.2°C. Rain is rare — about 1.9 wet days and 7.9mm across the month. Comfortable conditions for being outdoors all day.
June in Tustin averages a daily high of 26.1°C with nights around 16°C. Rain is rare — about 0.6 wet days and 0.9mm across the month. Comfortable conditions for being outdoors all day.
July in Tustin averages a daily high of 29°C with nights around 18°C. Rain is rare — about 0.4 wet days and 0.7mm across the month. Comfortable conditions for being outdoors all day.
August in Tustin averages a daily high of 30°C with nights around 18.4°C. Rain is rare — about 0.2 wet days and 1.7mm across the month. Comfortable conditions for being outdoors all day.
September in Tustin averages a daily high of 29.5°C with nights around 17.6°C. Rain is rare — about 0.7 wet days and 3.5mm across the month. Comfortable conditions for being outdoors all day.
October in Tustin averages a daily high of 27.1°C with nights around 15°C. Rain is rare — about 1.8 wet days and 12.9mm across the month. Comfortable conditions for being outdoors all day.
November in Tustin averages a daily high of 24°C with nights around 11.4°C. Rain is rare — about 2.9 wet days and 21mm across the month. Comfortable conditions for being outdoors all day.
December in Tustin averages a daily high of 20.8°C with nights around 8.8°C. Expect roughly 6 wet days totalling 60mm. Comfortable conditions for being outdoors all day.
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. Tustin peaks at 99.
Based on 30 years of records, April–July scores highest for comfort in Tustin, balancing daytime temperature against rainfall.
August is the warmest, averaging a daily high of 30°C.
February is the wettest, averaging 72.3mm of rain across roughly 6.3 wet days.
December is the coolest month, with average daily highs around 20.8°C.