Costa Mesa weather by month
What a typical year looks like in Costa Mesa, California: average highs and lows, rain and snow, and the warmest and coldest days on record. Normals are the 1991–2020 averages at SANTA ANA FIRE STATION, 10 km from Costa Mesa; records cover 1916–2026.
The year at a glance
- Precipitation a year
- 12.5 in319 mm
- Snow a year
- Rare
- Last spring freeze
- Rare
- First fall freeze
- Rare
- Heating degree days
- 926
- Cooling degree days
- 1,335
Freeze dates are medians (half of years earlier, half later). Degree days use a 65°F base; HVAC design temperatures here are 39°4° (heating, 99%) and 98°37° (cooling, 1%).
Month by month
Costa Mesa in January
Highs average 69°21° and lows 49°9°, with 2.9 in73 mm of precipitation in a typical January.
- Record high
- 96°36° (2003)
- Record low
- 16°−9° (1989)
- Heating degree days
- 198
- Cooling degree days
- 12
Costa Mesa in February
Highs average 69°21° and lows 50°10°, with 3.2 in80 mm of precipitation in a typical February.
- Record high
- 95°35° (1995)
- Record low
- 22°−6° (1989)
- Heating degree days
- 170
- Cooling degree days
- 13
Costa Mesa in March
Highs average 71°22° and lows 52°11°, with 1.7 in43 mm of precipitation in a typical March.
- Record high
- 100°38° (2026)
- Record low
- 28°−2° (1948)
- Heating degree days
- 129
- Cooling degree days
- 21
Costa Mesa in April
Highs average 73°23° and lows 54°12°, with 0.82 in21 mm of precipitation in a typical April.
- Record high
- 104°40° (1989)
- Record low
- 31°−1° (1953)
- Heating degree days
- 79
- Cooling degree days
- 40
Costa Mesa in May
Highs average 75°24° and lows 58°15°, with 0.29 in7.4 mm of precipitation in a typical May.
- Record high
- 105°41° (2004)
- Record low
- 35°2° (1950)
- Heating degree days
- 31
- Cooling degree days
- 75
Costa Mesa in June
Highs average 78°25° and lows 61°16°, with 0.08 in2 mm of precipitation in a typical June.
- Record high
- 112°44° (1917)
- Record low
- 39°4° (1950)
- Heating degree days
- 4
- Cooling degree days
- 139
Costa Mesa in July
Highs average 83°28° and lows 65°18°, with 0.03 in0.8 mm of precipitation in a typical July.
- Record high
- 114°46° (2018)
- Record low
- 42°6° (1948)
- Heating degree days
- 0
- Cooling degree days
- 267
Costa Mesa in August
Highs average 85°29° and lows 65°19°, with 0 in0 mm of precipitation in a typical August.
- Record high
- 106°41° (2020)
- Record low
- 45°7° (1918)
- Heating degree days
- 0
- Cooling degree days
- 308
Costa Mesa in September
Highs average 84°29° and lows 64°18°, with 0.12 in3 mm of precipitation in a typical September.
- Record high
- 113°45° (2024)
- Record low
- 40°4° (1948)
- Heating degree days
- 0
- Cooling degree days
- 266
Costa Mesa in OctoberThis month
Highs average 79°26° and lows 59°15°, with 0.5 in13 mm of precipitation in a typical October.
- Record high
- 106°41° (1958)
- Record low
- 34°1° (1924)
- Heating degree days
- 12
- Cooling degree days
- 148
Costa Mesa in November
Highs average 74°23° and lows 53°12°, with 0.79 in20 mm of precipitation in a typical November.
- Record high
- 101°38° (1966)
- Record low
- 24°−4° (1919)
- Heating degree days
- 89
- Cooling degree days
- 41
Costa Mesa in December
Highs average 68°20° and lows 48°9°, with 2.2 in55 mm of precipitation in a typical December.
- Record high
- 95°35° (1958)
- Record low
- 22°−6° (1918)
- Heating degree days
- 214
- Cooling degree days
- 5