Palo Alto, California climate: Normal weather by month, frost dates and records
Palo Alto's normal year runs from 39°F December nights to 79°F July afternoons, with 15.1 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 14.7°C, December lows of 4°C, July highs of 26°C, 384 mm of precipitation a year.
- NOAA stationPalo Alto
- Station IDUSC00046646
- Location37.44°N 122.14°W
- Elevation25 ft (8 m)
- From the center3 miles
- Population67,658
On October 23, the normal high in Palo Alto is 72°F and the normal low 47°F, and the chance of measurable rain or snow is 11%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Palo Alto.
- Jan 58° 39°
- Feb 61° 41°
- Mar 66° 44°
- Apr 70° 45°
- May 73° 50°
- Jun 79° 53°
- Jul 79° 56°
- Aug 79° 55°
- Sep 80° 53°
- Oct 74° 48°
- Nov 64° 43°
- Dec 58° 39°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like in Palo Alto each month?
July is the warmest month, with normal highs of 79°F; December the coldest, with normal lows of 39°F. The most precipitation falls in February (3.18 in), the least in July (0.00 in).
Each month has its own page with the day-by-day normals, the month's records and its recent years:
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 58°F | 39°F | 48.4°F | 2.95 | 10 | <1 | 5 | 9 h 50 min |
| February | 61°F | 41°F | 51.0°F | 3.18 | 10 | <1 | 2 | 10 h 50 min |
| March | 66°F | 44°F | 54.6°F | 2.19 | 8 | <1 | <1 | 11 h 50 min |
| April | 70°F | 45°F | 57.4°F | 0.97 | 5 | <1 | <1 | 13 h 10 min |
| May | 73°F | 50°F | 61.4°F | 0.44 | 3 | 1 | <1 | 14 h 10 min |
| June | 79°F | 53°F | 65.6°F | 0.10 | 1 | 3 | <1 | 14 h 40 min |
| July | 79°F | 56°F | 67.6°F | 0.00 | <1 | 2 | <1 | 14 h 30 min |
| August | 79°F | 55°F | 67.0°F | 0.03 | <1 | 2 | <1 | 13 h 40 min |
| September | 80°F | 53°F | 66.3°F | 0.07 | 1 | 4 | <1 | 12 h 30 min |
| October | 74°F | 48°F | 61.2°F | 0.64 | 3 | <1 | <1 | 11 h 20 min |
| November | 64°F | 43°F | 53.1°F | 1.60 | 6 | <1 | 1 | 10 h 10 min |
| December | 58°F | 39°F | 48.1°F | 2.95 | 10 | <1 | 6 | 9 h 40 min |
| Year (annual) | 70°F | 47°F | 58.5°F | 15.12 | 56 | 12 | 14 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | 14°C | 4°C | 9.1°C | 75 mm |
| February | 16°C | 5°C | 10.6°C | 81 mm |
| March | 19°C | 6°C | 12.6°C | 56 mm |
| April | 21°C | 7°C | 14.1°C | 25 mm |
| May | 23°C | 10°C | 16.3°C | 11 mm |
| June | 26°C | 12°C | 18.7°C | 3 mm |
| July | 26°C | 13°C | 19.8°C | 0 mm |
| August | 26°C | 13°C | 19.4°C | 1 mm |
| September | 26°C | 12°C | 19.1°C | 2 mm |
| October | 23°C | 9°C | 16.2°C | 16 mm |
| November | 18°C | 6°C | 11.7°C | 41 mm |
| December | 14°C | 4°C | 8.9°C | 75 mm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00046646; annual normals. Wet days: 0.01 inch or more; 90°F days and freezing nights: NOAA's day counts. Daylight: sunrise to sunset on the 15th, computed from the latitude.
When is the best weather to visit Palo Alto?
Normal highs sit between 65°F and 85°F in March, April, May, June, July, August, September and October. Of those, July has the fewest days with rain (0).
That is a measurement, not a recommendation: it counts the months whose normal afternoon high sits between 65°F and 85°F, where a light layer is enough by day.
Source: NOAA NCEI 1991-2020 monthly normals, station USC00046646.
When is the last frost in Palo Alto?
In Palo Alto, the last spring frost (32°F) comes after February 1 in half of years and after March 4 in one year in ten; the first autumn frost comes before December 7 in half of years and before November 20 in one year in ten.
Frost-free in half of yearsFrost in 1 to 9 years out of 10Frost most years
- Last spring frost, half of years after
- February 11 year in 10 after March 4; 9 in 10 after December 28
- First autumn frost, half of years before
- December 71 year in 10 before November 20; 9 in 10 before January 6
NOAA puts the median frost-free season at 310 days, and the season without a hard freeze (28°F) at 358 days.
A hard freeze (28°F) comes after January 4 in half of springs and before December 22 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Palo Alto in zones 9b to 10a across its 6 ZIP code areas (10a in 94303, the largest).
Frost dates for every NOAA station in California · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00046646; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026. A 10% date means one year in ten has a frost after it in spring or before it in autumn.
What hardiness zone is each Palo Alto ZIP code in?
The USDA's 2023 map gives each ZIP code area one zone. Palo Alto's 6 ZIP code areas run from zone 9b to 10a: 1 in 10a and 5 in 9b. Each ZIP's frost dates are in the frost tool.
Source: USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; ZIP areas in the place: Census Bureau 2020 ZCTA-to-place relationship file. A ZIP area counts when at least a tenth of its land (and 0.5 km²) lies in the place.
How hot and how cold does it get in Palo Alto?
In a normal year in Palo Alto, 12 days a year reach 90°F (1 of them 100°F or more), 14 nights fall to 32°F or colder and 56 days bring measurable precipitation.
- Days at 90°F or more
- 12a normal year
- Days at 100°F or more
- 1a normal year
- Nights at 32°F or colder
- 14a normal year
- Days that stay below freezing
- fewer than 1high of 32°F or less
- Days with 0.01 inch of precipitation
- 56a normal year
The highest temperature in this station's record (since 1953) is 107°F, on June 15, 1961; the lowest is 20°F, on December 23, 1990.
The wettest calendar year on that record is 1982, with 24.94 in; the snowiest season is 1961–62, with 1.5 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00046646; records: ACIS (NOAA Regional Climate Centers), station USC00046646. Records use complete months only; a month missing more than three days is left out.
How sunny is Palo Alto?
Over a year 80% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Palo Alto, 4.7 kWh per square metre a day. June is the sunniest month (84%) and December the cloudiest (74%). Among the 459 U.S. places of 50,000 or more, that ranks tied 125th (with 50 others) in sunshine.
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 76% | 2.5 |
| February | 77% | 3.4 |
| March | 79% | 4.6 |
| April | 82% | 6.0 |
| May | 81% | 6.7 |
| June | 84% | 7.3 |
| July | 78% | 6.5 |
| August | 77% | 5.8 |
| September | 82% | 5.1 |
| October | 83% | 4.0 |
| November | 81% | 2.8 |
| December | 74% | 2.1 |
Source: NASA POWER solar climatology, 2001-2020 (CERES SYN1deg). Satellite-based, for the 1-degree cell (about 100 km across) around the station, so it describes the area rather than the airport.
How much heating and cooling does Palo Alto need?
A normal year in Palo Alto brings 2,733 heating degree days, 49% fewer than the median U.S. place (5,373), and 364 cooling degree days, 60% fewer than the median (908). Five months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 3,364 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 515 | 0 |
| February | 392 | 0 |
| March | 325 | 1 |
| April | 234 | 7 |
| May | 136 | 24 |
| June | 47 | 65 |
| July | 15 | 94 |
| August | 16 | 78 |
| September | 35 | 74 |
| October | 138 | 20 |
| November | 357 | 0 |
| December | 524 | 0 |
| Year (annual) | 2,733 | 364 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00046646. A degree day is one degree of a day's mean temperature below 65°F (heating) or above it (cooling); utilities use them to estimate energy use.
How does Palo Alto's climate compare?
Palo Alto is warmer than 68 of the other 218 places with their own NOAA record in California, and wetter than 105. Across the 7,247 U.S. stations with normals, its annual mean of 58.5°F is warmer than 70%.
In the Köppen classification computed from these normals, Palo Alto is Csb: temperate, dry-summer, warm summer. What the classes mean.
Places with the most similar year elsewhere
Measured month by month on the normal high, low and precipitation, among places of 20,000 or more people in other states:
Source: NOAA NCEI 1991-2020 normals for every station PlainClimate covers. Similarity: the root-mean-square difference of the 36 monthly figures, precipitation weighted so an inch counts like 6°F.
Which places near Palo Alto share this climate record?
3 places have no NOAA station with 1991-2020 normals of their own, and this station is the nearest full record. A place's own climate can differ from these figures, by several degrees where it sits much higher or lower than the station, nearer the coast, or inside a large city's heat; for the larger places the next nearest records are named with their yearly mean, so the spread around them is visible, and places of 50,000 or more have their own page with NOAA's gridded normals.
- Menlo Park, CA33,040 people · 3 mi N
- East Palo Alto, CA29,296 people · 2 mi N
- Stanford, CA17,958 people · 2 mi SW
Source: Census Bureau 2024 Gazetteer (place centers) and Vintage 2024 population estimates. Distance and direction from the station to each place's center.
Questions about Palo Alto's climate
What is the coldest month in Palo Alto?
December, with a normal high of 58°F and a normal low of 39°F. The warmest is July (79°F by day, 56°F at night).
Does it snow in Palo Alto?
Rarely: NOAA's normal is no measurable snow a year.
What is the rainiest month in Palo Alto?
February, with 3.18 in of precipitation in a normal year; the driest is July with 0.00 in.
What plant hardiness zone is Palo Alto in?
The USDA's 2023 map puts Palo Alto in zones 9b to 10a across its 6 ZIP code areas (10a in 94303, the largest).
How late can frost come in Palo Alto?
In half of years the last 32°F night comes after February 1; in one year in ten it comes after March 4. Waiting until March 4 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Palo Alto in OctoberThis month day by day, its records and recent years
- California climateThe statewide normals and every place in the state
- Sunnyvale, CA6 miles from this station, 59.9°F a year
- Redwood City, CA6 miles from this station, 59.4°F a year
- Woodside, CA6 miles from this station, 60.1°F a year
- Newark, CA7 miles from this station, 59.9°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made