Annual mean 18°C · wettest around January · prevailing wind SW
Warmest
29.0 °C
Coldest
16.8 °C
Wettest
18%
Windiest
3.8 m/s
Prevailing
SW
3.1 m/s average
When this place is good five ratings · thirty-six ten-day sections · click a cell to read it
never good
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Every reading
bars actual · line feels-like, °Cchance of rain, %wind speed, m/ssky covered, %
The average temperature in Costa Mesa over the whole year is 18°C. August is the hottest month, with highs of about 28°C; January is the coldest, with lows of about 10°C. Costa Mesa has no sharply defined rainy season: the chance of rain on a given day runs from 1% in July, the driest month, to 15% in January, the wettest. Winds in Costa Mesa are highest in May, averaging 2.5 m/s (9 km/h), and lightest in November, at 1.6 m/s (6 km/h). The prevailing wind is from the SW. The clearest skies in Costa Mesa come in November, when the sky is typically 26% covered; May is the cloudiest month, at 53%.
Month by month Costa Mesa climate by month: average temperatures year round · click a month to read it
Month
High
Low
Feels like
Chance of rain
Cloud
Wind
Being outside
Sun
Walking
January
18°C
10°C
15°C
15%
34%
1.7 m/s
56
2
87
February
18°C
10°C
15°C
15%
35%
2.0 m/s
56
4
83
March
19°C
11°C
15°C
13%
42%
2.3 m/s
59
4
85
April
21°C
13°C
18°C
7%
40%
2.4 m/s
76
10
81
May
21°C
15°C
19°C
5%
53%
2.5 m/s
84
10
81
June
24°C
17°C
23°C
2%
46%
2.4 m/s
83
29
59
July
27°C
20°C
26°C
1%
31%
2.5 m/s
65
57
29
August
28°C
20°C
27°C
5%
27%
2.3 m/s
56
67
20
September
27°C
19°C
26°C
3%
33%
2.1 m/s
64
51
31
October
25°C
16°C
23°C
8%
30%
1.8 m/s
78
38
50
November
22°C
12°C
19°C
9%
26%
1.6 m/s
83
13
76
December
18°C
10°C
16°C
13%
32%
1.6 m/s
65
2
88
High and low are the warmest and coolest of four readings a day — midnight, 6am, noon and 6pm — so a true overnight low can sit a degree or two under them. Chance of rain, cloud and wind are the day’s average; feels-like and the three ratings (each out of 100: Good from 55, Ideal from 80) are read at midday.
Seasons, and the year in short Costa Mesa weather by season
Year round, Costa Mesa has days of about 18°C at their warmest in January, its coolest month, and 28°C in August, its warmest; the coolest hours of the day run from 10°C to 20°C through the year, and the average temperature over the year is 18°C around the clock. Rain is most likely around January and least likely around July. Every figure here is a decade of observations blended into one representative year, so it reads as what this date is usually like, not a forecast for one particular day.
Costa Mesa weather in winterDecember to February
High 18°CLow 10°CRain 14%
Winter in Costa Mesa has typical daily highs of about 18°C and lows of about 10°C, with a 14% chance of rain on a given day.
Costa Mesa weather in springMarch to May
High 20°CLow 13°CRain 8%
Spring in Costa Mesa has typical daily highs of about 20°C and lows of about 13°C, with a 8% chance of rain on a given day.
Costa Mesa weather in summerJune to August
High 26°CLow 19°CRain 3%
Summer in Costa Mesa has typical daily highs of about 26°C and lows of about 19°C, with a 3% chance of rain on a given day.
Costa Mesa weather in autumnSeptember to November
High 25°CLow 16°CRain 7%
Autumn in Costa Mesa has typical daily highs of about 25°C and lows of about 16°C, with a 7% chance of rain on a given day.
When is the rainy season in Costa Mesa?
Costa Mesa has no sharply defined rainy season: the chance of rain on a given day runs from 1% in July, the driest month, to 15% in January, the wettest.
What time of year is Costa Mesa windiest?
Winds in Costa Mesa are highest in May, averaging 2.5 m/s (9 km/h), and lightest in November, at 1.6 m/s (6 km/h). The prevailing wind is from the SW.
What is the average temperature in Costa Mesa year round?
The average temperature in Costa Mesa over the whole year is 18°C. August is the hottest month, with highs of about 28°C; January is the coldest, with lows of about 10°C.