Altadena Climate by Month
Altadena, California, United States
Hot summers and mild winters, with most rain from December to March.
Altadena has hot summers and mild winters, with most rain from December to March. Expect highs of 91°F (33°C) in August and 67°F (19°C) in December, with the coldest nights (December) near 43°F (6°C). Of the 16 in (413 mm) of rain in a typical year, 77% falls from December to March. May to September are almost completely dry.
- Warmest month
- 91°F(33°C)
- Average high, August
- Coldest nights
- 43°F(6°C)
- Average low, December
- Rain per year
- 16 in(413 mm)
- Wettest: February
- Humidity
- 48%
- Sunniest: June
Best and worst months in Altadena
Best for weatherThe most comfortable weather comes in April, May and November, with highs around 75°F (24°C) and about 0.9 in (24 mm) of rain a month.
Least pleasantFebruary and August are the least pleasant; August is the hottest, with highs of 91°F (33°C).
Comfort combines how close the afternoon high is to 75°F (24°C) with how much rain falls and how humid it is. See where the weather is best in May.
Temperature and rain through the year
Highs and lows (°F)
Average highAverage low
Rain (in per month)
Altadena weather by month
| Month | High | Low | Rain | Humidity | Sun |
|---|---|---|---|---|---|
| JanJanuary | 68°F(20°C) | 43°F(6°C) | 3.4 in(87 mm) | 47% | 2.8 |
| FebFebruary | 67°F(20°C) | 44°F(7°C) | 3.9 in(98 mm) | 53% | 3.4 |
| MarMarch | 70°F(21°C) | 46°F(8°C) | 2.7 in(68 mm) | 55% | 4.8 |
| AprAprilBest | 74°F(23°C) | 48°F(9°C) | 1.3 in(32 mm) | 49% | 5.9 |
| MayMayBest | 77°F(25°C) | 53°F(12°C) | 0.3 in(8 mm) | 52% | 6.4 |
| JunJune | 82°F(28°C) | 57°F(14°C) | 0.1 in(3 mm) | 49% | 6.9 |
| JulJuly | 89°F(32°C) | 61°F(16°C) | 0.1 in(2 mm) | 47% | 6.9 |
| AugAugust | 91°F(33°C) | 62°F(17°C) | 0.0 in(1 mm) | 45% | 6.7 |
| SepSeptember | 88°F(31°C) | 60°F(15°C) | 0.2 in(4 mm) | 45% | 5.5 |
| OctOctober | 81°F(27°C) | 54°F(12°C) | 0.6 in(15 mm) | 44% | 4.2 |
| NovNovemberBest | 73°F(23°C) | 47°F(8°C) | 1.2 in(31 mm) | 39% | 3.3 |
| DecDecember | 67°F(19°C) | 43°F(6°C) | 2.5 in(64 mm) | 48% | 2.6 |
1991–2020 averages. Sun is solar radiation in kWh/m² per day. Highlighted: the most comfortable months.
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