Santa Rosa weather in January

In January, Santa Rosa sees average daytime highs of 57°F and overnight lows near 40°F, with 5.7 in of rain across 10.3 wet days and about 9.6 hours of daylight. It is the 11th-warmest and 3rd-wettest month of the year here.

Day-to-day highs hold fairly steady near 57°F through the month. The sky is clear or mostly clear about 32% of the time in January, and the air most often feels dry.

Daylight stretches from about 9 h 24 min at the start of January to 10 hours by month's end. Set against the rest of the year, January is Santa Rosa's 12th-clearest and 8th-windiest month. For the whole year in context, see Santa Rosa's year-round climate.

Daytime high
57°
11th warmest
Overnight low
40°
2nd coldest
Rainfall
5.7 in
10.3 wet days
Daylight
9 h 36 min
7:32 AM – 5:08 PM
Cloud cover
60%
12th clearest
Wind
4 mph
8th windiest
Solar energy
2.25 kWh/m²
Travel score
4.0
out of 10

Santa Rosa is city in and county seat of Sonoma County, California, United States.

Density
1,657/km²
people per km²
Founded
1868

Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.

Temperature in January

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near 57°F through the month.

A typical January day in Santa Rosa reaches about 57°F in the afternoon and slips back to 40°F overnight — a 17°F spread between the day's warmth and the night's chill. On most days the high lands between 50°F and 65°F. Set against its neighbours, January runs on par with December and about 3°F cooler than February.

20°30°40°50°60°70°151015202531
Avg high (°F)Avg low (°F)
15639
25639
35639
45639
55639
65639
75639
85639
95640
105640
115640
125640
135640
145640
155740
165740
175740
185740
195740
205740
215740
225740
235740
245840
255840
265840
275840
285840
295841
305841
315941

Santa Rosa weather by month

How January compares with the rest of the year at a glance. January is the 11th-warmest and 3rd-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysDaylight (hours)Travel score
Jan57° / 40°5.710.39.64.0
Feb60° / 42°5.89.310.54.7
Mar63° / 44°4.49.511.75.7
Apr67° / 46°1.95.6137.0
May73° / 51°1.13.614.18.2
Jun80° / 55°0.31.214.68.5
Jul83° / 57°0.00.114.47.8
Aug83° / 57°0.00.213.57.8
Sep81° / 55°0.10.612.38.6
Oct74° / 50°1.43.2118.5
Nov63° / 44°3.06.29.96.2
Dec56° / 39°5.910.19.43.9

Cloud cover in January

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 32% of the time in January, the cloudiest month of the year.

Beyond those clear spells, partly cloudy skies cover about 10% of January, with mostly cloudy or overcast conditions the remaining 57%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
14258
24258
34258
44060
54060
64060
74060
84159
94159
104159
114258
124258
134258
144357
154456
164456
174456
184456
194456
204456
214456
224456
234456
244357
254456
264456
274357
284357
294357
304456
314555

Chance of precipitation in January

Any precipitation

Santa Rosa gets around 5.7 in of rain over 10.3 wet days in January. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 33% and peaks near 34% on the wettest days.

0%10%20%30%40%151015202531
Rain chance (%)
132
233
333
433
533
633
733
833
933
1033
1133
1233
1334
1434
1534
1634
1734
1834
1934
2034
2134
2234
2334
2433
2533
2632
2732
2831
2931
3030
3130

Humidity in January

DryComfortableHumidMuggyOppressiveMiserable

Most of January feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.

By dew point, January lands in the dry band about 100% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)
1991
2991
3991
4991
5991
6991
7991
8991
9991
101000
111000
121000
131000
141000
151000
161000
171000
181000
191000
201000
211000
221000
231000
241000
251000
261000
271000
281000
291000
30991
31991

Wind in January

Winds average 4 mph in January.

Across January, daily wind ranges from about 4 mph on the calmest days to 4 mph at its breeziest. It stays fairly steady from day to day.

0246810151015202531
Wind speed (mph)Feels
14calm
24calm
34calm
44calm
54calm
64calm
74calm
84calm
94calm
104calm
114calm
124calm
134calm
144calm
154calm
164calm
174calm
184calm
194calm
204calm
214calm
224calm
234calm
244calm
254calm
264calm
274calm
284calm
294calm
304calm
314calm

Sunrise & sunset in January

DaylightNight

Daylight runs from about 9 h 24 min at the start of January to 10 hours by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 36 minutes over January. Sunrise moves from 7:33 AM to 7:24 AM, and sunset from 4:55 PM to 5:24 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
19.47:334:55
29.47:334:56
39.47:334:56
49.47:344:57
59.47:344:58
69.47:344:59
79.47:345:00
89.47:345:01
99.57:345:01
109.57:335:02
119.57:335:03
129.57:335:04
139.57:335:05
149.67:335:06
159.67:335:07
169.67:325:08
179.67:325:09
189.67:325:10
199.77:315:11
209.77:315:12
219.77:305:13
229.77:305:14
239.87:295:15
249.87:295:16
259.87:285:17
269.87:285:19
279.97:275:20
289.97:265:21
299.97:265:22
3010.07:255:23
3110.07:245:24

Solar energy in January

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in January, about 2.25 kWh/m².

For context, solar energy here swings from a low near 2.08 kWh/m² to a high of 8.01 kWh/m² in June across the year — January's 2.25 kWh/m² sits near the bottom.

0123151015202531
Solar energy (kWh/m²)Level
12.1Moderate
22.1Moderate
32.1Moderate
42.1Moderate
52.1Moderate
62.1Moderate
72.1Moderate
82.1Moderate
92.1Moderate
102.1Moderate
112.1Moderate
122.2Moderate
132.2Moderate
142.2Moderate
152.2Moderate
162.2Moderate
172.3Moderate
182.3Moderate
192.3Moderate
202.3Moderate
212.4Moderate
222.4Moderate
232.4Moderate
242.5Moderate
252.5Moderate
262.5Moderate
272.6Moderate
282.6Moderate
292.6Moderate
302.7Moderate
312.7Moderate
Planning a trip in January

Hazard calendar for Santa Rosa

In seasonPeak

In January, Santa Rosa sits inside its rainy season season. The full year is below, with each hazard's peak months called out.

Santa Rosa's rainy season runs November–March, when most of the year's rain falls.

Rainy season
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec

Is January a good time to visit Santa Rosa?

Our two travel scores rate January for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal).

4.0
Sightseeing
11th-best month of the year
0.0
Beach & pool
12th-best month of the year

January is a reasonable time to visit Santa Rosa for sightseeing.

What to pack for Santa Rosa in January

From January's temperature range, rain chance, sun and wind — what's worth putting in the bag.

In January, Santa Rosa sees daytime highs around 57°F and nights near 40°F. Worth packing: a warm layer and rain gear. About 10 days see rain.

a warm layerrain gear

Sea temperature near Santa Rosa in January

The nearest coast averages about 53°F in January — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea at the nearest coast (about 23 mi away) is warmest in September at about 55°F and coldest in May near 51°F.

The water stays below 68°F all year — cool enough that most swimmers want a wetsuit.

50°52°54°56°JanFebMarAprMayJunJulAugSepOctNovDecbracing
Sea temperature (°F)Comfort
Jan53Bracing
Feb53Bracing
Mar53Bracing
Apr51Bracing
May51Bracing
Jun51Bracing
Jul53Bracing
Aug54Bracing
Sep55Bracing
Oct55Bracing
Nov54Bracing
Dec53Bracing

UV index in Santa Rosa in January

LowModerateHighVery highExtreme

Clear-sky midday UV in January peaks around 2. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Santa Rosa peaks around June 23 at about 10 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 17 at about 2 (moderate).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 9 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highExtremeVery highHighModerateJun 23UV 10Dec 17UV 2
UV index (midday)Level
Jan2Moderate
Feb4Moderate
Mar5Moderate
Apr6High
May9Very high
Jun10Extreme
Jul10Extreme
Aug9Very high
Sep6High
Oct5High
Nov2Moderate
Dec2Low

Air quality in Santa Rosa in January

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where January falls, not just the annual average.

Air quality in Santa Rosa is worst in September — around 24 µg/m³ PM2.5 (moderate), about 4.1× the cleanest month (June, 6 µg/m³).

Modeled monthly averages (CAMS reanalysis, 2015–2024).

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodSep 1623 µg/m³Jun 116 µg/m³
PM2.5 (µg/m³)Level
Jan8Good
Feb9Good
Mar9Good
Apr7Good
May7Good
Jun6Good
Jul9Good
Aug17Moderate
Sep24Moderate
Oct16Moderate
Nov9Good
Dec7Good
Location & terrain

Where is Santa Rosa?

Santa Rosa sits at 38.4°N, 122.7°W, 164 ft above sea level, in United States. The nearest listed city is Rohnert Park, 6.8 mi away.

Topography around Santa Rosa

How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of Santa Rosa.

Within 2 miles, the terrain around Santa Rosa has only modest variations in elevation — a maximum elevation change of 449 ft around an average of 184 ft above sea level; within 10 miles, large variations in elevation — a maximum elevation change of 2,687 ft; within 50 miles, very significant variations in elevation — a maximum elevation change of 4,895 ft.

The land around Santa Rosa is covered by artificial surfaces (65%) and trees (28%) within 2 miles, trees (44%) and grassland (34%) within 10 miles, and trees (38%), water (27%) and grassland (26%) within 50 miles.

2 miles
449 ft
10 miles
2,687 ft
50 miles
4,895 ft
treesgrasslandcroplandartificial surfaceswaterwetland
January weather nearby: Rohnert Park 6.8 mi · Windsor 9.3 mi · Agua Caliente 15 mi · Petaluma 15 mi · Novato 24 mi · Napa 25 mi · American Canyon 30 mi · San Rafael 34 mi

United States travel facts

Power plugs
Type A / B
120 V · 60 Hz
Prices
≈ 100% of US
price level, 2025
GDP per capita
$90,027
2025
Happiness
6.8 / 10
World Happiness, 2025
Safe drinking water
98%
of population, 2024
Homicide rate
5.8
per 100k, 2023
Road deaths
12.7
per 100k/yr, 2019
Income group
High
World Bank
Religion
Protestant 47%unaffiliated 23%Roman Catholic 21%Jewish 2%

Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.

Data sources

Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Santa Rosa (38.4405°, -122.7144°, elevation 164 ft), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google. Sea temperatures are the NOAA OISST v2.1 1991–2020 monthly climatology (public domain), sampled at the nearest ocean point. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Monthly air-quality (PM2.5) seasonality is from the CAMS EAC4 reanalysis (Copernicus Atmosphere Monitoring Service), scaled to the WHO annual mean where available. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).