Photo: pelle68 · CC BY-SA 3.0Costa Mesa’s winters are milder and less snowy than most of the U.S.
A typical July afternoon reaches 78°, a January night drops to 48°, and snow is almost unheard of.
A year in Costa Mesa at a glance
Each month’s typical high and low, and what it brings.
What stands out about Costa Mesa’s climate
Compared with towns across the U.S., with Costa Mesa’s place in California beside it.
What a year in Costa Mesa feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
Frost is rare
Frost and day counts come from NOAA’s station at Santa Ana John Wayne Airport, 2.8 miles from the city’s center point, at about the same height.
The 2023 USDA map puts Costa Mesa’s center in zone 10b: the coldest night of a typical winter, averaged over 1991–2020, reaches about 37°. Plant labels use the zone; frost dates tell you when to plant.
90° days by month
Average days at 90° or more
About 11 inches of rain a year
February is the wettest month and August the driest. Rain falls on about 35 days a year. Snow is rare: about 0.0" in a normal year at Santa Ana Fire Stn, CA, so most winters see none.
Rain + melted snow by month
Inches of water
Heating and cooling a home in Costa Mesa
50% of the work is heating. No month averages under 55°.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Santa Ana John Wayne Airport.
Living with Costa Mesa’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
Zone 10b. Frost almost never comes, so tender plants can often stay out through winter.
Months with highs of 62–84° and lows of 40° or more: January, February, March, April, May, June, July, August, September, October, November and December. 19 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Costa Mesa from natural hazards, earthquakes are the largest share (57%). Normals are averages; the hazards page covers the extremes.
Natural hazards →Costa Mesa and its neighbors
Irvine has the coldest January nights next door (47°, 1° colder) and Irvine the hottest July afternoons (83°, 6° warmer). Differences under a degree are within what the 5 km grid can tell apart. Tap a town to see its climate.
Climates most like Costa Mesa’s, farther away
TownRatings’ own comparison of NOAA 1991–2020 normals, not a NOAA product: places of 5,000+ at least 150 miles away, one per state, closest on January low, July high, precipitation and snow.
| Town | Jan. low | July high | Precip. | Snow |
|---|---|---|---|---|
| Costa Mesa, CA | 48° | 78° | 11" | 0.0" |
| Makawao, HI | 53° | 75° | 23" | 0.0" |
| Sequim, WA | 34° | 71° | 18" | 1.4" |
| Winston, OR | 37° | 86° | 33" | 0.0" |
| Alpine, TX | 30° | 90° | 15" | 2.2" |
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value. Snow and frost-free days come from the nearest weather station, so neighbors often share them.
Warmer than it used to be
The last 30 years in Costa Mesa averaged 2.1° warmer than the 1900s. The biggest change is in January (+3.1°).
A bigger shift than in 94% of U.S. towns.
Change by month
The two periods overlap (1991–2000 is in both), which makes the gap a little smaller than it would be between separate periods. In a city of 109,000 people, part of the change is the city itself: pavement and buildings hold heat (the urban heat island).
How Costa Mesa compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Costa Mesa’s place among California’s.
Costa Mesa weather by month
Highs, lows and precipitation from NOAA’s grid at Costa Mesa’s center; snow, wet days and snow on the ground from Santa Ana Fire Stn, CA. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 68° | 48° | 2.5" | 0.0" | 6 | 0 | 55° – 62° |
| February | 67° | 49° | 2.9" | 0.0" | 7 | 0 | 53° – 64° |
| March | 68° | 51° | 1.6" | 0.0" | 5 | 0 | 55° – 67° |
| April | 70° | 53° | 0.7" | 0.0" | 3 | 0 | 58° – 65° |
| May | 71° | 57° | 0.2" | 0.0" | 2 | 0 | 61° – 69° |
| June | 74° | 60° | 0.1" | 0.0" | 1 | 0 | 64° – 71° |
| July | 78° | 64° | 0.0" | 0.0" | 1 | 0 | 67° – 76° |
| August | 80° | 64° | 0.0" | 0.0" | 0 | 0 | 69° – 75° |
| September | 80° | 63° | 0.1" | 0.0" | 1 | 0 | 68° – 76° |
| October | 77° | 58° | 0.4" | 0.0" | 2 | 0 | 64° – 74° |
| November | 73° | 52° | 0.7" | 0.0" | 3 | 0 | 57° – 65° |
| December | 68° | 47° | 2.0" | 0.0" | 6 | 0 | 54° – 62° |
| Year | 73° | 55° | 11.2" | 0.0" | 35 | 0 |
How much a month can swing
A normal is an average. March swings the most: from 1991 to 2020 its average ranged from 55° to 67°. August is the most reliable, staying within 6°.
Where Costa Mesa’s numbers come from
Normals are 30-year averages, not a forecast. How TownRatings reads climate data →
- Temperatures and precipitation: NOAA’s gridded 1991–2020 normals for the 5 km cell at Costa Mesa’s center.
- Snow: Santa Ana Fire Stn, CA.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Santa Ana John Wayne Airport, 2.8 miles from the city’s center point, at about the same height; the nearest station that passes our checks for distance, height and agreement with the grid.
- Growing zone: USDA Plant Hardiness Zone Map, 2023. USDA Agricultural Research Service and PRISM Group, Oregon State University, prism.oregonstate.edu/phzm, accessed 8 Oct 2026.
- Then and now: NOAA’s gridded normals for 1901–2000 at the same cell.
- Storms and extremes: FEMA National Risk Index (expected annual losses to buildings).
Common questions about Costa Mesa’s climate
What is the weather like in Costa Mesa?
A typical July afternoon reaches 78°, a January night drops to 48°, and snow is almost unheard of. Milder January nights than 95% of U.S. towns; cooler July afternoons than 96% of U.S. towns.
How cold does it get in Costa Mesa in winter?
December nights average 47°. A night at 32° or below comes in only some winters (0.0 a year on average). In the coldest December of the last 30 years the month averaged 54°.
How much snow does Costa Mesa get?
About 0.0 inches in a normal winter at Santa Ana Fire Stn, CA, so most winters see none.
How hot does it get in Costa Mesa?
July, with a typical high of 78° and a low of 64°. About 13 days a year reach 90° (Santa Ana John Wayne Airport).
When is the first and last frost in Costa Mesa?
Most years have no frost at all: a 32° night comes in about 0% of winters at Santa Ana John Wayne Airport, usually in December or January.
What growing zone is Costa Mesa in?
Zone 10b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about 37°.
What is the best time of year to visit Costa Mesa?
By one simple rule (highs of 62–84° and lows of 40° or more), January, February, March, April, May, June, July, August, September, October, November and December. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Costa Mesa getting warmer?
Yes: 1991–2020 averaged 2.1° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 94% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Costa Mesa.
Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000; USDA/PRISM 2023 hardiness zones; FEMA National Risk Index. Today’s forecast: National Weather Service.