Photo: Coolcaesar at en.wikipedia · CC BY-SA 3.0Los Altos’ winters are milder than most of the U.S.; July afternoons average 82°
A typical July afternoon reaches 82°, a January night drops to 40°.
A year in Los Altos at a glance
Each month’s typical high and low, and what it brings.
What stands out about Los Altos’ climate
Compared with towns across the U.S., with Los Altos’ place in California beside it.
What a year in Los Altos feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
A freeze most winters
Frost and day counts come from NOAA’s station at Moffett Federal Airfield, CA, 4 miles from the town’s center, 150 ft lower.
The 2023 USDA map puts Los Altos’ center in zone 9b: the coldest night of a typical winter, averaged over 1991–2020, reaches about 29°. 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 22 inches of rain a year
February is the wettest month and July the driest.
Rain + melted snow by month
Inches of water
Heating and cooling a home in Los Altos
84% of the work is heating. Months averaging under 55° run from November through March.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Moffett Federal Airfield, CA.
Living with Los Altos’ climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
Zone 9b. Frost comes about 7 winters in 10, so tender plants can often stay out through winter.
Months with highs of 62–84° and lows of 40° or more: February, March, April, May, June, July, August, September, October and November. 1.4 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Los Altos from natural hazards, earthquakes are the largest share (55%); heat waves, cold waves, winter storms and ice storms together are 1%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Los Altos and its neighbors
Cupertino the hottest July afternoons (83°, 1° warmer). Differences under a degree are within what the 5 km grid can tell apart. Tap a town to see its climate.
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 Los Altos averaged 1.9° warmer than the 1900s. The biggest change is in August (+2.2°).
A bigger shift than in 84% 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 Los Altos compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Los Altos’ place among California’s.
Los Altos weather by month
Highs, lows and precipitation from NOAA’s grid at Los Altos’ center. 1991–2020 normals.
| Month | High | Low | Rain + melt | 30-yr range |
|---|---|---|---|---|
| January | 60° | 40° | 4.4" | 47° – 54° |
| February | 62° | 42° | 4.5" | 48° – 57° |
| March | 66° | 43° | 3.5" | 50° – 59° |
| April | 69° | 45° | 1.6" | 53° – 60° |
| May | 73° | 48° | 0.7" | 57° – 65° |
| June | 79° | 51° | 0.2" | 62° – 68° |
| July | 82° | 54° | 0.0" | 65° – 71° |
| August | 82° | 54° | 0.0" | 66° – 72° |
| September | 81° | 53° | 0.1" | 64° – 71° |
| October | 76° | 49° | 0.9" | 59° – 68° |
| November | 66° | 43° | 2.2" | 48° – 58° |
| December | 59° | 39° | 4.4" | 45° – 54° |
| Year | 71° | 47° | 22.4" |
How much a month can swing
A normal is an average. November swings the most: from 1991 to 2020 its average ranged from 48° to 58°. July is the most reliable, staying within 6°.
Where Los Altos’ 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 Los Altos’ center.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Moffett Federal Airfield, CA, 4 miles from the town’s center, 150 ft lower; 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 Los Altos’ climate
What is the weather like in Los Altos?
A typical July afternoon reaches 82°, a January night drops to 40°. Milder January nights than 88% of U.S. towns; cooler July afternoons than 84% of U.S. towns.
How cold does it get in Los Altos in winter?
December nights average 39°. About 2 nights a year reach 32° or below. In the coldest December of the last 30 years the month averaged 45°.
How hot does it get in Los Altos?
July, with a typical high of 82° and a low of 54°. About 9 days a year reach 90° (Moffett Federal Airfield, CA).
When is the first and last frost in Los Altos?
There is no reliable frost date: a 32° night comes in about 70% of winters at Moffett Federal Airfield, CA, so most years bring a freeze but some pass without one.
What growing zone is Los Altos in?
Zone 9b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about 29°.
What is the best time of year to visit Los Altos?
By one simple rule (highs of 62–84° and lows of 40° or more), February, March, April, May, June, July, August, September, October and November. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Los Altos getting warmer?
Yes: 1991–2020 averaged 1.9° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 84% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Los Altos.
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.