Rio Oso weather by month
What a typical year looks like in Rio Oso, California: average highs and lows, rain and snow, and the warmest and coldest days on record. Normals are the 1991–2020 averages at Marysville Airport (asos), 17 km from Rio Oso; records cover 2000–2026.
The year at a glance
- Precipitation a year
- 20.1 in510 mm
- Snow a year
- Rare
- Last spring freeze
- Feb 27
- First fall freeze
- Nov 24
- Heating degree days
- 2,550
- Cooling degree days
- 1,499
Freeze dates are medians (half of years earlier, half later). Degree days use a 65°F base; HVAC design temperatures here are 27°−3° (heating, 99%) and 106°41° (cooling, 1%).
Month by month
Rio Oso in January
Highs average 56°13° and lows 38°3°, with 3.8 in97 mm of precipitation in a typical January.
- Record high
- 76°24° (2009)
- Record low
- 19°−7° (2012)
- Heating degree days
- 563
- Cooling degree days
- 0
Rio Oso in February
Highs average 60°16° and lows 41°5°, with 3.7 in93 mm of precipitation in a typical February.
- Record high
- 80°27° (2016)
- Record low
- 24°−4° (2022)
- Heating degree days
- 399
- Cooling degree days
- 0
Rio Oso in March
Highs average 66°19° and lows 43°6°, with 2.9 in74 mm of precipitation in a typical March.
- Record high
- 89°32° (2026)
- Record low
- 29°−2° (2002)
- Heating degree days
- 317
- Cooling degree days
- 1
Rio Oso in April
Highs average 73°23° and lows 46°8°, with 1.4 in36 mm of precipitation in a typical April.
- Record high
- 96°36° (2004)
- Record low
- 32°0° (2001)
- Heating degree days
- 184
- Cooling degree days
- 19
Rio Oso in May
Highs average 82°28° and lows 52°11°, with 0.93 in24 mm of precipitation in a typical May.
- Record high
- 107°42° (2021)
- Record low
- 35°2° (2022)
- Heating degree days
- 49
- Cooling degree days
- 116
Rio Oso in June
Highs average 90°32° and lows 58°14°, with 0.28 in7.1 mm of precipitation in a typical June.
- Record high
- 111°44° (2009)
- Record low
- 43°6° (2005)
- Heating degree days
- 6
- Cooling degree days
- 276
Rio Oso in July
Highs average 96°36° and lows 61°16°, with 0 in0 mm of precipitation in a typical July.
- Record high
- 113°45° (2021)
- Record low
- 51°11° (2008)
- Heating degree days
- 0
- Cooling degree days
- 417
Rio Oso in August
Highs average 95°35° and lows 60°15°, with 0.05 in1.3 mm of precipitation in a typical August.
- Record high
- 110°43° (2020)
- Record low
- 47°8° (2022)
- Heating degree days
- 0
- Cooling degree days
- 372
Rio Oso in September
Highs average 90°32° and lows 56°13°, with 0.11 in2.8 mm of precipitation in a typical September.
- Record high
- 115°46° (2022)
- Record low
- 41°5° (2007)
- Heating degree days
- 6
- Cooling degree days
- 235
Rio Oso in OctoberThis month
Highs average 79°26° and lows 49°10°, with 1 in26 mm of precipitation in a typical October.
- Record high
- 104°40° (2001)
- Record low
- 32°0° (2006)
- Heating degree days
- 86
- Cooling degree days
- 62
Rio Oso in November
Highs average 64°18° and lows 41°5°, with 2.2 in56 mm of precipitation in a typical November.
- Record high
- 86°30° (2018)
- Record low
- 26°−3° (2015)
- Heating degree days
- 368
- Cooling degree days
- 1
Rio Oso in December
Highs average 55°13° and lows 38°3°, with 3.7 in93 mm of precipitation in a typical December.
- Record high
- 73°23° (2020)
- Record low
- 20°−7° (2009)
- Heating degree days
- 572
- Cooling degree days
- 0