San Francisco weather in December

In December, San Francisco sees average daytime highs of 30°C and overnight lows near 18°C, with 128 mm of rain across 9.6 wet days and about 14 hours of daylight. It is the 2nd-warmest and 2nd-wettest month of the year here.

Day-to-day highs hold fairly steady near 30°C through the month. The sky is clear or mostly clear about 49% of the time in December, and the air most often feels humid.

Daylight stretches from about 13 h 54 min at the start of December to 14 hours by month's end. Set against the rest of the year, December is San Francisco's 6th-clearest and 6th-windiest month. For the whole year in context, see San Francisco's year-round climate.

Daytime high
30°
2nd warmest
Overnight low
18°
10th coldest
Rainfall
128 mm
9.6 wet days
Daylight
14 hours
6:03 AM – 8:06 PM
Cloud cover
44%
6th clearest
Wind
12 km/h
6th windiest
Solar energy
7.19 kWh/m²
Travel score
5.5
out of 10

San Francisco is city in Argentina.

Founded
1886

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 30°C through the month.

A typical December day in San Francisco reaches about 30°C in the afternoon and slips back to 18°C overnight — a 11°C spread between the day's warmth and the night's chill. On most days the high lands between 25°C and 34°C. Set against its neighbours, December runs about 2°C warmer than November and on par with January.

10°15°20°25°30°35°151015202531
Avg high (°C)Avg low (°C)
12917
22917
32917
42917
52917
62917
72918
82918
92918
102918
112918
122918
132918
142918
153018
163018
173018
183018
193019
203019
213019
223019
233019
243019
253019
263019
273019
283019
293019
303019
313019

San Francisco weather by month

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

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan30° / 19°1199.113.85.3
Feb29° / 19°1159.113.15.8
Mar27° / 17°1389.212.26.8
Apr24° / 14°1008.211.37.4
May20° / 11°475.510.47.1
Jun18° / 304.3106.6
Jul17° / 203.510.26.7
Aug20° / 393.810.97.6
Sep22° / 11°515.411.87.8
Oct25° / 14°1169.612.87.2
Nov28° / 16°1198.913.66.6
Dec30° / 18°1289.6145.5

Cloud cover in December

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 49% of the time in December.

Beyond those clear spells, partly cloudy skies cover about 16% of December, with mostly cloudy or overcast conditions the remaining 35%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
16634
26634
36634
46733
56733
66634
76634
86733
96733
106733
116733
126733
136733
146634
156634
166634
176634
186535
196535
206535
216436
226535
236436
246436
256436
266436
276337
286337
296337
306436
316436

Chance of precipitation in December

Any precipitation

San Francisco gets around 128 mm of rain over 9.6 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 32% and peaks near 33% on the wettest days.

0%10%20%30%40%151015202531
Rain chance (%)
130
230
330
430
530
630
730
830
930
1031
1131
1231
1331
1432
1532
1632
1732
1832
1933
2033
2133
2233
2333
2433
2533
2633
2733
2832
2932
3032
3132

Humidity in December

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, December lands in the humid band about 28% of days. Sticky, muggy-or-worse air turns up on roughly 32% of them.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)Miserable (%)
12829261520
22828261520
32728261530
42728271530
52627271630
62627281640
72526281640
82426291650
92326301650
102225301750
112125311760
122025311860
131924321870
141724321970
151624332080
161523332180
171423322290
181322322390
1913223124100
2012213125110
2111213027110
2210202928120
2310202829131
249192729141
259192630151
269192531161
278192431171
288182431181
298182332181
308182332191
317172233191

Wind in December

Winds average 12 km/h in December.

Across December, daily wind ranges from about 12 km/h on the calmest days to 13 km/h at its breeziest. It stays fairly steady from day to day.

051015151015202531
Wind speed (km/h)Feels
113light breeze
213light breeze
313light breeze
413light breeze
513light breeze
613light breeze
712light breeze
812light breeze
912light breeze
1012light breeze
1112light breeze
1212light breeze
1312light breeze
1412light breeze
1512light breeze
1612light breeze
1712light breeze
1812light breeze
1912light breeze
2012light breeze
2112light breeze
2212light breeze
2312light breeze
2412light breeze
2512light breeze
2612light breeze
2712calm
2812calm
2912calm
3012calm
3112calm

Sunrise & sunset in December

DaylightNight

Daylight runs from about 13 h 54 min at the start of December to 14 hours by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 6 minutes over December. Sunrise moves from 6:01 AM to 6:11 AM, and sunset from 7:55 PM to 8:12 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
113.96:017:55
213.96:017:56
313.96:017:57
413.96:017:57
513.96:017:58
614.06:017:59
714.06:018:00
814.06:018:00
914.06:028:01
1014.06:028:02
1114.06:028:02
1214.06:028:03
1314.06:038:04
1414.06:038:04
1514.06:038:05
1614.06:038:06
1714.06:048:06
1814.06:048:07
1914.06:058:07
2014.06:058:08
2114.06:058:08
2214.06:068:09
2314.06:068:09
2414.06:078:10
2514.06:078:10
2614.06:088:10
2714.06:088:11
2814.06:098:11
2914.06:108:12
3014.06:108:12
3114.06:118:12

Solar energy in December

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in December, about 7.19 kWh/m² — the sunniest month for solar.

For context, solar energy here swings from a low near 2.55 kWh/m² to a high of 7.19 kWh/m² in December across the year — December's 7.19 kWh/m² sits near the top of that range.

02468151015202531
Solar energy (kWh/m²)Level
17.1Intense
27.1Intense
37.1Intense
47.1Intense
57.1Intense
67.2Intense
77.2Intense
87.2Intense
97.2Intense
107.2Intense
117.2Intense
127.2Intense
137.2Intense
147.2Intense
157.2Intense
167.2Intense
177.2Intense
187.2Intense
197.2Intense
207.2Intense
217.2Intense
227.2Intense
237.2Intense
247.2Intense
257.2Intense
267.2Intense
277.2Intense
287.2Intense
297.1Intense
307.1Intense
317.1Intense
Planning a trip in December

Is December a good time to visit San Francisco?

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

5.5
Sightseeing
11th-best month of the year
7.2
Beach & pool
2nd-best month of the year

December is a reasonable time to visit San Francisco for sightseeing. The water and warmth also suit a beach or pool day.

What to pack for San Francisco in December

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

In December, San Francisco sees daytime highs around 30°C and nights near 18°C. Pack light clothes and sun protection. Worth having: rain gear. About 10 days see rain.

light clothessun protectionrain gear

UV index in San Francisco in December

LowModerateHighVery highExtreme

Clear-sky midday UV in December peaks around 13 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in San Francisco peaks around January 17 at about 14 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near June 21 at about 3 (moderate).

The index reaches 3 or more — the level where the WHO recommends sun protection — every month of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecExtremeModerateHighVery highExtremeJan 17UV 14Jun 21UV 3
UV index (midday)Level
Jan14Extreme
Feb13Extreme
Mar11Extreme
Apr7High
May4Moderate
Jun3Moderate
Jul3Moderate
Aug5Moderate
Sep7High
Oct10Very high
Nov11Extreme
Dec13Extreme
Location & terrain

Where is San Francisco?

San Francisco sits at 31.4°S, 62.1°W, 120 m above sea level, in Argentina. The nearest listed city is San Jorge, 57 km away.

Topography around San Francisco

How much the land rises and falls, and what covers it, within 3, 16 and 80 km of San Francisco.

Within 3 km, the terrain around San Francisco has only modest variations in elevation — a maximum elevation change of 13 m around an average of 114 m above sea level; within 16 km, only modest variations in elevation — a maximum elevation change of 24 m; within 80 km, only modest variations in elevation — a maximum elevation change of 103 m.

The land around San Francisco is covered by artificial surfaces (50%) and cropland (30%) within 3 km, cropland (94%) within 16 km, and cropland (88%) within 80 km.

3 km
13 m
16 km
24 m
80 km
103 m
treesgrasslandcroplandartificial surfaceswater
December weather nearby: San Jorge 57 km · Rafaela 60 km · Sunchales 73 km · Las Varillas 78 km · Morteros 80 km · Arroyito 92 km · Gálvez 106 km · Esperanza 109 km

Argentina travel facts

Travel advisory
Level 1
Exercise Normal Precautions
Power plugs
Type C / I
220 V · 50 Hz
Prices
≈ 46% of US
price level, 2025
GDP per capita
$14,898
2025
Happiness
6.4 / 10
World Happiness, 2025
Homicide rate
4.5
per 100k, 2023
Road deaths
14.1
per 100k/yr, 2019
Income group
Upper middle
World Bank
English
High
EF EPI 575
Religion
Roman Catholic 63%none 19%Evangelical 15%Jehovah's Witness and Church of Jesus Christ 1%

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 San Francisco (-31.425°, -62.084°, elevation 120 m), 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. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).