San_Ramon_ weather in December

In December, San_Ramon_ sees average daytime highs of 27°C and overnight lows near 20°C, with 75 mm of rain across 16.3 wet days and about 11.4 hours of daylight. It is the 6th-warmest and 9th-wettest month of the year here.

Day-to-day highs hold fairly steady near 27°C through the month. The sky is clear or mostly clear about 40% of the time in December, and the air most often feels muggy.

Daylight stretches from about 11 h 30 min at the start of December to 11 h 24 min by month's end. Set against the rest of the year, December is San_Ramon_'s 4th-clearest and 4th-windiest month. For the whole year in context, see San_Ramon_'s year-round climate.

Daytime high
27°
6th warmest
Overnight low
20°
2nd coldest
Rainfall
75 mm
16.3 wet days
Daylight
11 h 24 min
5:52 AM – 5:16 PM
Cloud cover
51%
4th clearest
Wind
5 km/h
4th windiest
Solar energy
4.45 kWh/m²
Travel score
5.7
out of 10

Temperature in December

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near 27°C through the month.

A typical December day in San_Ramon_ reaches about 27°C in the afternoon and slips back to 20°C overnight — a 7°C spread between the day's warmth and the night's chill. On most days the high lands between 26°C and 29°C. Set against its neighbours, December runs on par with November and about 1°C cooler than January.

15°20°25°30°151015202531
Avg high (°C)Avg low (°C)
12720
22720
32720
42720
52720
62720
72720
82720
92720
102720
112720
122720
132720
142720
152720
162720
172720
182720
192720
202720
212720
222720
232720
242720
252720
262720
272820
282820
292820
302820
312820

San_Ramon_ weather by month

How December compares with the rest of the year at a glance. December is the 6th-warmest and 9th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan28° / 20°216.711.56.8
Feb29° / 20°154.211.76.4
Mar30° / 20°247.911.95.6
Apr29° / 21°9820.712.24.1
May28° / 21°38129.612.53.3
Jun27° / 21°41729.812.63.3
Jul27° / 21°32029.912.53.3
Aug27° / 21°39830.412.33.3
Sep27° / 20°44229.812.13.3
Oct26° / 20°50330.711.83.3
Nov26° / 20°26726.511.53.9
Dec27° / 20°7516.311.45.7

Cloud cover in December

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 40% of the time in December.

Beyond those clear spells, partly cloudy skies cover about 22% of December, with mostly cloudy or overcast conditions the remaining 38%. Skies tend to open up as the month goes on.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
14456
24753
34852
44951
55050
65248
75347
85347
95446
105545
115545
125743
135842
145941
156040
166238
176337
186535
196634
206832
217030
227129
237327
247327
257426
267525
277525
287525
297723
307723
317723

Chance of precipitation in December

Any precipitation

San_Ramon_ gets around 75 mm of rain over 16.3 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 53% and peaks near 69% on the wettest days. The odds ease toward the end of the month.

0%20%40%60%80%151015202531
Rain chance (%)
169
268
367
466
565
664
763
862
961
1060
1159
1258
1357
1456
1555
1654
1752
1851
1949
2048
2147
2245
2344
2443
2541
2640
2739
2838
2937
3036
3135

Humidity in December

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, December lands in the muggy band about 65% of days. Sticky, muggy-or-worse air turns up on roughly 66% of them.

0%25%50%75%100%151015202531
Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
1014815
2015805
3016804
4017794
5018793
6019783
7120772
8121762
9122752
10123751
11124741
12126721
13127711
14129691
15130690
16132670
17133660
18135640
19136630
20138610
21139600
22141580
23142570
24144550
25146530
26247510
27249490
28251470
29253450
30255430
31257410

Wind in December

Winds average 5 km/h in December.

Across December, daily wind ranges from about 5 km/h on the calmest days to 6 km/h at its breeziest. It stays fairly steady from day to day.

0246810151015202531
Wind speed (km/h)Feels
15calm
25calm
35calm
45calm
55calm
65calm
75calm
85calm
95calm
105calm
115calm
125calm
135calm
145calm
155calm
165calm
175calm
185calm
195calm
205calm
216calm
226calm
236calm
246calm
256calm
266calm
276calm
286calm
296calm
306calm
316calm

Sunrise & sunset in December

DaylightNight

Daylight runs from about 11 h 30 min at the start of December to 11 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 5:44 AM to 5:58 AM, and sunset from 5:11 PM to 5:24 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
111.55:445:11
211.45:455:11
311.45:455:12
411.45:465:12
511.45:465:12
611.45:475:13
711.45:475:13
811.45:485:13
911.45:485:14
1011.45:495:14
1111.45:495:14
1211.45:505:15
1311.45:505:15
1411.45:515:16
1511.45:515:16
1611.45:525:16
1711.45:525:17
1811.45:535:17
1911.45:535:18
2011.45:545:18
2111.45:545:19
2211.45:555:19
2311.45:555:20
2411.45:555:20
2511.45:565:21
2611.45:565:21
2711.45:575:22
2811.45:575:22
2911.45:585:23
3011.45:585:23
3111.45:585:24

Solar energy in December

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in December, about 4.45 kWh/m².

For context, solar energy here swings from a low near 3.82 kWh/m² to a high of 6.19 kWh/m² in March across the year — December's 4.45 kWh/m² falls in the middle.

024151015202531
Solar energy (kWh/m²)Level
14.1Bright
24.1Bright
34.1Bright
44.2Bright
54.2Bright
64.2Bright
74.2Bright
84.2Bright
94.3Bright
104.3Bright
114.3Bright
124.3Bright
134.3Bright
144.4Bright
154.4Bright
164.4Bright
174.4Bright
184.5Bright
194.5Bright
204.5Bright
214.5Bright
224.6Bright
234.6Bright
244.6Bright
254.6Bright
264.7Bright
274.7Bright
284.7Bright
294.7Bright
304.8Bright
314.8Bright
Planning a trip in December

Hazard calendar for San_Ramon_

In seasonPeak

None of San_Ramon_'s seasonal hazards are active in December. The full-year calendar below shows when the rainy season, cyclone risk and dust haze do peak.

San_Ramon_'s rainy season runs May–November, 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 San_Ramon_?

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

5.7
Sightseeing
3rd-best month of the year
5.9
Beach & pool
4th-best month of the year

December is a reasonable time to visit San_Ramon_ for sightseeing.

What to pack for San_Ramon_ in December

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

In December, San_Ramon_ sees daytime highs around 27°C and nights near 20°C. Pack light clothes and rain gear. About 16 days see rain.

light clothesrain gear

Sea temperature near San_Ramon_ in December

The nearest coast averages about 28°C 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 29 km away) is warmest in April at about 29°C and coldest in November near 28°C.

The water stays above 20°C all year — warm enough for a swim any month.

26°28°30°JanFebMarAprMayJunJulAugSepOctNovDecwarmtropicalcomfortable to swim
Sea temperature (°C)Comfort
Jan29Tropical
Feb29Tropical
Mar29Tropical
Apr29Tropical
May29Tropical
Jun29Tropical
Jul29Tropical
Aug29Tropical
Sep29Tropical
Oct28Tropical
Nov28Warm
Dec28Tropical

UV index in San_Ramon_ in December

LowModerateHighVery highExtreme

Clear-sky midday UV in December peaks around 10 (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_Ramon_ peaks around February 22 at about 14 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 17 at about 10 (very high).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecExtremeFeb 22UV 14Dec 17UV 10
UV index (midday)Level
Jan11Extreme
Feb14Extreme
Mar14Extreme
Apr14Extreme
May12Extreme
Jun13Extreme
Jul12Extreme
Aug12Extreme
Sep12Extreme
Oct12Extreme
Nov11Extreme
Dec10Very high

Air quality in San_Ramon_ 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 San_Ramon_ is worst in May — around 18 µg/m³ PM2.5 (moderate), about 2.0× the cleanest month (January, 9 µg/m³).

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

01020JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodMay 1617 µg/m³Jan 19 µg/m³
PM2.5 (µg/m³)Level
Jan9Good
Feb10Good
Mar11Good
Apr16Moderate
May18Moderate
Jun16Moderate
Jul17Moderate
Aug15Moderate
Sep14Moderate
Oct12Moderate
Nov11Good
Dec9Good
Location & terrain

Where is San_Ramon_?

San_Ramon_ sits at 10.1°N, 84.5°W, 0 m above sea level, in Costa Rica. The nearest listed city is Esparza, 24 km away.

EsparzaQuesadaAlajuelaSan Rafael AbajoChacaritaMercedes NorteSan FranciscoHeredia

Topography around San_Ramon_

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

Within 3 km, the terrain around San_Ramon_ has significant variations in elevation — a maximum elevation change of 294 m around an average of 1,066 m above sea level; within 16 km, very significant variations in elevation — a maximum elevation change of 1,914 m; within 80 km, extreme variations in elevation — a maximum elevation change of 3,414 m.

The land around San_Ramon_ is covered by trees (53%), artificial surfaces (25%) and grassland (21%) within 3 km, trees (68%) and grassland (27%) within 16 km, and trees (61%) within 80 km.

3 km
294 m
16 km
1,914 m
80 km
3,414 m
treesgrasslandcroplandartificial surfaceswatermangroves
December weather nearby: Esparza 24 km · Quesada 27 km · Alajuela 29 km · San Rafael Abajo 35 km · Chacarita 36 km · Mercedes Norte 38 km · San Francisco 39 km · Heredia 40 km

Costa Rica travel facts

Travel advisory
Level 2
Exercise Increased Caution
Power plugs
Type A / B
120 V · 60 Hz
Prices
≈ 59% of US
price level, 2025
GDP per capita
$19,970
2025
Happiness
7.4 / 10
World Happiness, 2025
Safe drinking water
81%
of population, 2024
Homicide rate
17.7
per 100k, 2023
Road deaths
14.8
per 100k/yr, 2019
Income group
High
World Bank
English
Moderate
EF EPI 516
Religion
Roman Catholic 48%none 27%Evangelical and Pentecostal 20%other 3%

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_Ramon_ (10.088°, -84.4702°, elevation 0 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. 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).