Few U.S. towns get less rain and snow than San Mateo: 12 inches a year
In January the night’s low is typically 15°. Winter nights are cold: in January they are colder than in 84% of U.S. towns. Compared with 1901–2000, the average now sits 1.4° higher. Picnics, hikes and garden evenings come into their own from June to September, with highs of 75–84°.
A year in San Mateo at a glance
Each month’s typical high and low, and what it brings.
What stands out about San Mateo’s climate
Compared with towns across the U.S., with San Mateo’s place in New Mexico beside it.
What a year in San Mateo feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 137 frost-free days a year
In half of years the last 32° night comes by May 17 and the first by October 3. Frost and day counts come from Grants Airport, 19 miles away.
The 2023 USDA map puts San Mateo’s center in zone 6a: the coldest night of a typical winter, averaged over 1991–2020, reaches about −6°. Plant labels use the zone; frost dates tell you when to plant.
Freezing nights by month
Average nights at or below 32°
90° days by month
Average days at 90° or more
About 12 inches of rain a year
August is the wettest month and February the driest.
Rain + melted snow by month
Inches of water
Heating and cooling a home in San Mateo
89% of the work is heating, so the furnace matters far more than the air conditioner. Months averaging under 55° run from October through April.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Grants Airport.
Living with San Mateo’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
137 frost-free days in zone 6a. The last frost comes by May 17 in half of years, so many gardeners wait a week or two past that to set out tomatoes. The first fall frost comes by Oct 3.
Months with highs of 62–84° and lows of 40° or more: June, July, August and September.
Parks & trails →Of the yearly building losses FEMA expects in San Mateo from natural hazards, river flooding is the largest share (76%); heat waves, cold waves, winter storms and ice storms together are 11%. Normals are averages; the hazards page covers the extremes.
Natural hazards →San Mateo and similar climates
TownRatings has no climate map of the towns around San Mateo yet.
Temperatures and precipitation come from NOAA’s 5 km grid; snow and day counts from the stations named on this page.
Warmer than it used to be
The last 30 years in San Mateo averaged 1.4° warmer than the 1900s. The biggest change is in March (+2.5°).
A bigger shift than in 51% 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.
How San Mateo compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with San Mateo’s place among New Mexico’s.
San Mateo weather by month
Highs, lows and precipitation from NOAA’s grid at San Mateo’s center. 1991–2020 normals.
| Month | High | Low | Rain + melt | 30-yr range |
|---|---|---|---|---|
| January | 42° | 15° | 0.7" | 22° – 35° |
| February | 46° | 19° | 0.5" | 27° – 38° |
| March | 55° | 24° | 0.6" | 36° – 44° |
| April | 62° | 30° | 0.6" | 42° – 51° |
| May | 72° | 39° | 0.5" | 51° – 61° |
| June | 83° | 49° | 0.5" | 62° – 70° |
| July | 84° | 54° | 2.2" | 65° – 73° |
| August | 81° | 52° | 2.4" | 64° – 70° |
| September | 75° | 45° | 1.4" | 56° – 63° |
| October | 65° | 34° | 0.8" | 46° – 54° |
| November | 52° | 23° | 0.7" | 31° – 44° |
| December | 42° | 15° | 0.7" | 22° – 35° |
| Year | 63° | 33° | 11.5" |
How much a month can swing
A normal is an average. November swings the most: from 1991 to 2020 its average ranged from 31° to 44°. August is the most reliable, staying within 6°.
Where San Mateo’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 San Mateo’s center.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Grants Airport, 19 miles from the town’s center, 770 ft lower; no station nearby passes every check; this is the nearest one in the same valley, flagged above.
- 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 San Mateo’s climate
What is the weather like in San Mateo?
A typical July afternoon reaches 84°, a January night drops to 15°. Colder January nights than 84% of U.S. towns; cooler July afternoons than 60% of U.S. towns.
How cold does it get in San Mateo in winter?
January nights average 15°. About 182 nights a year reach 32° or below and 5 reach 0° or below. In the coldest January of the last 30 years the month averaged 22°.
How hot does it get in San Mateo?
July, with a typical high of 84° and a low of 54°. About 59 days a year reach 90° and 4 reach 100° (Grants Airport).
When is the first and last frost in San Mateo?
In half of years the last spring frost (32°) comes by May 17 and the first fall frost by October 3, about 137 frost-free days, at Grants Airport.
What growing zone is San Mateo in?
Zone 6a on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −6°.
What is the best time of year to visit San Mateo?
By one simple rule (highs of 62–84° and lows of 40° or more), June, July, August and September. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is San Mateo getting warmer?
Yes: 1991–2020 averaged 1.4° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 51% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in San Mateo.
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.