Climateby Month

Santa Rosa, CA climate by month

NOAA 1991-2020 normals · 165 ft elevation

Summers in Santa Rosa are warm; winters are cool. Highs peak at 84°F in August and fall to 58°F in December. The wettest month is January (about 13 wet days) and the driest is July (about 0). Snow is rare. The most comfortable time to visit is April and May.

Warmest month
84°F
August normal high
Coldest month
37°F
December normal low
Wet days a year
78
39.9 in of precipitation
Muggy days a year
0
dew point 65°F or higher

How warm is Santa Rosa?

Normal highs range from 58°F in December to 84°F in August.

30°40°50°60°70°80°90° January: normal high 58°F (14°C), low 37°F (3°C) 58° 37° February: normal high 62°F (17°C), low 39°F (4°C) March: normal high 66°F (19°C), low 41°F (5°C) April: normal high 70°F (21°C), low 42°F (6°C) May: normal high 75°F (24°C), low 46°F (8°C) June: normal high 81°F (27°C), low 48°F (9°C) July: normal high 83°F (28°C), low 51°F (11°C) August: normal high 84°F (29°C), low 50°F (10°C) 84° 50° September: normal high 84°F (29°C), low 48°F (9°C) October: normal high 78°F (26°C), low 44°F (7°C) November: normal high 67°F (19°C), low 40°F (4°C) December: normal high 58°F (14°C), low 37°F (3°C) JFMAMJJASOND

Bars run from the normal low to the normal high for each month.

How rainy is Santa Rosa?

January has the most wet days (about 13); the year brings about 40 in of precipitation.

January: 13 wet days 13 February: 12 wet days March: 11 wet days April: 7 wet days May: 4 wet days June: 2 wet days July: 0 wet days 0 August: 1 wet days September: 2 wet days October: 4 wet days November: 9 wet days December: 13 wet days JFMAMJJASOND

Wet day: at least 0.01 in of rain or melted snow, counted from daily records 1991-2020.

How humid is Santa Rosa?

Muggy days (dew point 65°F or higher) are rare in any month.

January: 0 muggy days 0 February: 0 muggy days March: 0 muggy days April: 0 muggy days May: 0 muggy days June: 0 muggy days July: 0 muggy days August: 0 muggy days September: 0 muggy days October: 0 muggy days November: 0 muggy days December: 0 muggy days JFMAMJJASOND

Muggy day: daily mean dew point of 65°F or higher, from hourly observations 1991-2020 at Sonoma County Airport, 6.8 mi NW of the city center.

How much daylight?

Daylight ranges from about 9.5 hours in December to 14.8 hours in June.

January: 9.8 hours of daylight February: 10.8 hours of daylight March: 12.0 hours of daylight April: 13.2 hours of daylight May: 14.3 hours of daylight June: 14.8 hours of daylight 14.8 July: 14.5 hours of daylight August: 13.6 hours of daylight September: 12.4 hours of daylight October: 11.2 hours of daylight November: 10.1 hours of daylight December: 9.5 hours of daylight 9.5 JFMAMJJASOND
See all numbers
Monthly climate normals and day counts for Santa Rosa, 1991-2020
MonthHighLowPrecip.Wet daysMuggy daysDaylight
January 58°F37°F 7.9 in13 0 9.8 h
February 62°F39°F 7.5 in12 0 10.8 h
March 66°F41°F 5.2 in11 0 12.0 h
April 70°F42°F 2.6 in7 0 13.2 h
May 75°F46°F 1.4 in4 0 14.3 h
June 81°F48°F 0.4 in2 0 14.8 h
July 83°F51°F 0.01 in0 0 14.5 h
August 84°F50°F 0.06 in1 0 13.6 h
September 84°F48°F 0.2 in2 0 12.4 h
October 78°F44°F 2.0 in4 0 11.2 h
November 67°F40°F 4.4 in9 0 10.1 h
December 58°F37°F 8.3 in13 0 9.5 h

High and low: NOAA 1991-2020 normal daily high and low. Wet days: at least 0.01 in of rain or melted snow. Muggy days: daily mean dew point 65°F or higher.

Best months to visit Santa Rosa

By our comfort score, the best months are April and May.

Comfort score by month (0-100) and its parts, in days per month
MonthScoreComfortableNotable rainHot or cold
Jan 49790
Feb 591290
Mar 681780
Apr 782051
May 801922
Jun 701216
Jul 681106
Aug 661108
Sep 60918
Oct 651534
Nov 661860
Dec 46590

Score = 40 × share of comfortable days + 25 × share of days without notable rain + 20 × share of days neither hot (90°F+) nor cold (high 40°F or below) + 15 × daylight. How the score works.

Frost dates in Santa Rosa

The last spring frost typically comes around Feb 25, and the first fall frost around Dec 1, leaving 279 frost-free days in a typical year.

Frost and freeze dates for Santa Rosa
Typical date1 year in 10
Last spring frost (32°F)Feb 25after Mar 29
First fall frost (32°F)Dec 1before Nov 10
Last hard freeze (28°F)Jan 20after Feb 24
First hard freeze (28°F)Dec 16before Nov 26
Frost-free season279 daysunder 244 days

"Typical" is the date with a 50% chance of a later spring frost (or earlier fall frost). Planting after the "1 year in 10" spring date gives a 90% chance of no further frost. The Old Farmer's Almanac publishes 30% dates, which fall between our typical and 1-in-10 dates.

Station: Santa Rosa (USC00047965), NOAA 1991-2020 freeze probabilities. Frost dates for every city in California.

Hottest and coldest readings, 1991-2020

The highest reading was 114°F (September 6, 2020); the lowest was 18°F (December 9, 2013, and 2 other days).

From the temperature station's daily records with NOAA quality flags removed. Not an all-time record.

Near Santa Rosa

Similar climates elsewhere

Where the numbers come from

  • Temperature and rain: Graton (USC00043578), 8.2 mi W of the city center, 200 ft . NOAA normals and daily records, 1991-2020.
  • Snowfall, snow depth and frost dates: Santa Rosa (USC00047965), 1.1 mi N of the city center, 166 ft . NOAA normals and daily records, 1991-2020.
  • Humidity and wind by hour and cloud cover: Travis AFB (USW00023202), 44 mi ESE of the city center, 59 ft (106 ft lower than the city). NOAA normals and daily records, 1991-2020.
  • Daily humidity and wind: Sonoma County Airport (724957-23213), 6.8 mi NW of the city center, 119 ft . Hourly observations, 1991-2020.

Distances from the city center (USGS). Methodology · Report an error