Rohnert Park weather in December

In December, Rohnert Park sees average daytime highs of 56°F and overnight lows near 42°F, with 5.5 in of rain across 10.4 wet days and about 9.4 hours of daylight. It is the 11th-warmest and 2nd-wettest month of the year here.

Day-to-day highs hold fairly steady near 56°F through the month. The sky is clear or mostly clear about 35% of the time in December, and the air most often feels dry.

Daylight stretches from about 9 h 30 min at the start of December to 9 h 24 min by month's end. Set against the rest of the year, December is Rohnert Park's 10th-clearest and 7th-windiest month. For the whole year in context, see Rohnert Park's year-round climate.

Daytime high
56°
11th warmest
Overnight low
42°
1st coldest
Rainfall
5.5 in
10.4 wet days
Daylight
9 h 18 min
7:27 AM – 4:47 PM
Cloud cover
58%
10th clearest
Wind
5 mph
7th windiest
Solar energy
2.11 kWh/m²
Travel score
3.9
out of 10

Rohnert Park is city in Sonoma County, California, United States.

Density
2,337/km²
people per km²
Founded
1962

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

Temperature in December

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near 56°F through the month.

A typical December day in Rohnert Park reaches about 56°F in the afternoon and slips back to 42°F overnight — a 15°F spread between the day's warmth and the night's chill. On most days the high lands between 51°F and 62°F. Set against its neighbours, December runs about 6°F cooler than November and on par with January.

30°40°50°60°70°151015202531
Avg high (°F)Avg low (°F)
15843
25843
35843
45843
55842
65742
75742
85742
95742
105742
115742
125642
135642
145642
155641
165641
175641
185641
195641
205641
215641
225641
235641
245641
255640
265640
275640
285640
295641
305641
315641

Rohnert Park weather by month

How December compares with the rest of the year at a glance. December is the 11th-warmest and 2nd-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysDaylight (hours)Travel score
Jan56° / 42°5.410.39.63.9
Feb59° / 43°5.69.310.54.5
Mar61° / 45°4.29.311.75.3
Apr64° / 47°1.95.6136.5
May68° / 50°1.03.314.17.7
Jun73° / 53°0.2114.69.0
Jul75° / 55°0.00.114.49.5
Aug75° / 55°0.00.213.59.5
Sep75° / 54°0.10.512.39.3
Oct71° / 51°1.23.1118.2
Nov62° / 45°2.86.29.95.9
Dec56° / 42°5.510.49.43.9

Cloud cover in December

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 35% of the time in December.

Beyond those clear spells, partly cloudy skies cover about 12% of December, with mostly cloudy or overcast conditions the remaining 53%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
15149
24951
35050
44951
54852
64753
74654
84555
94555
104555
114555
124456
134555
144654
154654
164753
174753
184852
194852
204753
214852
224852
234852
244951
254951
264852
274753
284753
294654
304555
314555

Chance of precipitation in December

Any precipitation

Rohnert Park gets around 5.5 in of rain over 10.4 wet days in December. 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 36% on the wettest days.

0%10%20%30%40%50%151015202531
Rain chance (%)
130
231
331
432
533
634
735
835
936
1036
1136
1236
1336
1436
1536
1635
1735
1834
1934
2033
2133
2232
2332
2432
2532
2631
2731
2831
2931
3032
3132

Humidity in December

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, December lands in the dry band about 98% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)
1973
2973
3973
4973
5973
6973
7973
8973
9973
10973
11973
12973
13973
14982
15982
16982
17982
18982
19982
20982
21982
22982
23982
24982
25982
26982
27982
28982
29982
30982
31982

Wind in December

Winds average 5 mph in December.

Across December, daily wind ranges from about 5 mph on the calmest days to 5 mph at its breeziest. It stays fairly steady from day to day.

0246810151015202531
Wind speed (mph)Feels
15calm
25calm
35calm
45calm
55calm
65calm
75calm
85calm
95calm
105calm
115calm
125calm
135calm
145calm
155calm
165calm
175calm
185calm
195calm
205calm
215calm
225calm
235calm
245calm
255calm
265calm
275calm
285calm
295calm
305calm
315calm

Sunrise & sunset in December

DaylightNight

Daylight runs from about 9 h 30 min at the start of December to 9 h 24 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 6 minutes over December. Sunrise moves from 7:15 AM to 7:33 AM, and sunset from 4:46 PM to 4:55 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
19.57:154:46
29.57:164:46
39.57:174:46
49.57:184:46
59.57:184:46
69.47:194:46
79.47:204:46
89.47:214:46
99.47:224:46
109.47:224:46
119.47:234:46
129.47:244:46
139.47:254:46
149.47:254:47
159.37:264:47
169.37:274:47
179.37:274:48
189.37:284:48
199.37:284:48
209.37:294:49
219.37:304:49
229.37:304:50
239.37:304:50
249.37:314:51
259.37:314:51
269.37:324:52
279.37:324:52
289.37:324:53
299.37:334:54
309.47:334:54
319.47:334:55

Solar energy in December

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in December, about 2.11 kWh/m² — the year's lowest.

For context, solar energy here swings from a low near 2.11 kWh/m² to a high of 7.93 kWh/m² in June across the year — December's 2.11 kWh/m² sits near the bottom.

0123151015202531
Solar energy (kWh/m²)Level
12.3Moderate
22.2Moderate
32.2Moderate
42.2Moderate
52.1Moderate
62.1Moderate
72.1Moderate
82.1Moderate
92.1Moderate
102.1Moderate
112.1Moderate
122.0Moderate
132.0Moderate
142.0Moderate
152.0Moderate
162.0Moderate
172.0Moderate
182.1Moderate
192.1Moderate
202.1Moderate
212.1Moderate
222.1Moderate
232.1Moderate
242.1Moderate
252.1Moderate
262.1Moderate
272.1Moderate
282.1Moderate
292.1Moderate
302.1Moderate
312.2Moderate
Planning a trip in December

Hazard calendar for Rohnert Park

In seasonPeak

In December, Rohnert Park sits inside its rainy season season. The full year is below, with each hazard's peak months called out.

Rohnert Park'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 December a good time to visit Rohnert Park?

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

3.9
Sightseeing
11th-best month of the year
0.0
Beach & pool
11th-best month of the year

December is a weaker month for outdoor sightseeing in Rohnert Park.

What to pack for Rohnert Park in December

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

In December, Rohnert Park sees daytime highs around 56°F and nights near 42°F. Worth packing: a warm layer and rain gear. About 10 days see rain.

a warm layerrain gear

Sea temperature near Rohnert Park in December

The nearest coast averages about 53°F in December — 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 Rohnert Park in December

LowModerateHighVery highExtreme

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

Under clear skies, the midday UV index in Rohnert Park 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 Rohnert Park in December

GoodModeratePoorUnhealthyVery unhealthy

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

Air quality in Rohnert Park 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 Rohnert Park?

Rohnert Park sits at 38.3°N, 122.7°W, 105 ft above sea level, in United States. The nearest listed city is Santa Rosa, 6.8 mi away.

Topography around Rohnert Park

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

Within 2 miles, the terrain around Rohnert Park has only modest variations in elevation — a maximum elevation change of 253 ft around an average of 128 ft above sea level; within 10 miles, large variations in elevation — a maximum elevation change of 2,457 ft; within 50 miles, very significant variations in elevation — a maximum elevation change of 4,895 ft.

The land around Rohnert Park is covered by artificial surfaces (47%) and grassland (23%) within 2 miles, grassland (47%) and trees (28%) within 10 miles, and trees (34%), water (31%) and grassland (24%) within 50 miles.

2 miles
253 ft
10 miles
2,457 ft
50 miles
4,895 ft
treesgrasslandcroplandartificial surfacesbare terrainwaterwetland
December weather nearby: Santa Rosa 6.8 mi · Petaluma 8.1 mi · Agua Caliente 12 mi · Windsor 16 mi · Novato 17 mi · Napa 23 mi · American Canyon 27 mi · San Rafael 27 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 Rohnert Park (38.3396°, -122.7011°, elevation 105 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).