| Month | High | Low | Rain | Wet days | Score |
|---|---|---|---|---|---|
| January | 18° | 10.1° | — | — | 88 |
| February | 18° | 9.1° | — | — | 88 |
| March | 20.1° | 9.6° | — | — | 94 |
| April | 22.5° | 10.4° | — | — | 94 |
| May | 25.4° | 11.9° | — | — | 94 |
| June | 29.2° | 14.1° | — | — | 85 |
| July | 33.5° | 17.2° | — | — | 68 |
| August | 34.2° | 18.1° | — | — | 65 |
| September | 31.8° | 17.4° | — | — | 75 |
| October | 27.2° | 15.3° | — | — | 93 |
| November | 22.3° | 12.5° | — | — | 94 |
| December | 17.9° | 9.8° | — | — | 87 |
January in Simi Valley averages a daily high of 18°C with nights around 10.1°C. Comfortable conditions for being outdoors all day.
February in Simi Valley averages a daily high of 18°C with nights around 9.1°C. Comfortable conditions for being outdoors all day.
March in Simi Valley averages a daily high of 20.1°C with nights around 9.6°C. Comfortable conditions for being outdoors all day.
April in Simi Valley averages a daily high of 22.5°C with nights around 10.4°C. Comfortable conditions for being outdoors all day.
May in Simi Valley averages a daily high of 25.4°C with nights around 11.9°C. Comfortable conditions for being outdoors all day.
June in Simi Valley averages a daily high of 29.2°C with nights around 14.1°C. Comfortable conditions for being outdoors all day.
July in Simi Valley averages a daily high of 33.5°C with nights around 17.2°C. Generally workable, with some weather to plan around.
August in Simi Valley averages a daily high of 34.2°C with nights around 18.1°C. Generally workable, with some weather to plan around.
September in Simi Valley averages a daily high of 31.8°C with nights around 17.4°C. Comfortable conditions for being outdoors all day.
October in Simi Valley averages a daily high of 27.2°C with nights around 15.3°C. Comfortable conditions for being outdoors all day.
November in Simi Valley averages a daily high of 22.3°C with nights around 12.5°C. Comfortable conditions for being outdoors all day.
December in Simi Valley averages a daily high of 17.9°C with nights around 9.8°C. 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. Simi Valley peaks at 94.
Based on 30 years of records, October–May scores highest for comfort in Simi Valley, balancing daytime temperature against rainfall.
August is the warmest, averaging a daily high of 34.2°C.
January is the wettest, averaging —mm of rain across roughly — wet days.
December is the coolest month, with average daily highs around 17.9°C.