San Carlos weather in May

In May, San Carlos sees average daytime highs of 66°F and overnight lows near 52°F, with 0.8 in of rain across 3.3 wet days and about 14 hours of daylight. It is the 6th-warmest and 8th-wettest month of the year here.

Day-to-day highs hold fairly steady near 66°F through the month. The sky is clear or mostly clear about 51% of the time in May, and the air most often feels dry.

Daylight stretches from about 13 h 30 min at the start of May to 14 h 24 min by month's end. Set against the rest of the year, May is San Carlos's 6th-clearest and 1st-windiest month. For the whole year in context, see San Carlos's year-round climate.

Daytime high
66°
6th warmest
Overnight low
52°
7th coldest
Rainfall
0.8 in
3.3 wet days
Daylight
14 hours
5:05 AM – 7:06 PM
Cloud cover
42%
6th clearest
Wind
6 mph
1st windiest
Solar energy
7.11 kWh/m²
Travel score
7.4
out of 10

San Carlos is city in San Mateo County, California, United States.

Density
2,096/km²
people per km²
Founded
1925

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

Temperature in May

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near 66°F through the month.

A typical May day in San Carlos reaches about 66°F in the afternoon and slips back to 52°F overnight — a 15°F spread between the day's warmth and the night's chill. On most days the high lands between 59°F and 75°F. Set against its neighbours, May runs about 3°F warmer than April and about 4°F cooler than June.

40°50°60°70°80°151015202531
Avg high (°F)Avg low (°F)
16651
26651
36651
46651
56651
66651
76651
86651
96651
106651
116651
126651
136652
146652
156652
166652
176652
186652
196652
206652
216752
226752
236752
246753
256753
266753
276753
286753
296753
306853
316853

San Carlos weather by month

How May compares with the rest of the year at a glance. May is the 6th-warmest and 8th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysDaylight (hours)Travel score
Jan57° / 45°3.99.49.74.1
Feb59° / 47°4.29.310.64.5
Mar61° / 48°3.29.111.75.3
Apr63° / 49°1.65.612.96.4
May66° / 52°0.83.3147.4
Jun70° / 54°0.20.914.58.5
Jul73° / 56°0.00.214.39.1
Aug74° / 57°0.00.113.49.2
Sep74° / 57°0.10.412.39.2
Oct71° / 54°0.93118.2
Nov63° / 49°2.06106.1
Dec57° / 46°3.79.39.54.1

Cloud cover in May

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 51% of the time in May.

Beyond those clear spells, partly cloudy skies cover about 17% of May, with mostly cloudy or overcast conditions the remaining 32%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
16733
26733
36733
46733
56733
66733
76733
86634
96634
106634
116535
126535
136634
146535
156535
166634
176634
186634
196634
206634
216733
226832
236931
246931
257030
267030
277129
287129
297228
307228
317426

Chance of precipitation in May

Any precipitation

San Carlos gets around 0.8 in of rain over 3.3 wet days in May. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 10% and peaks near 12% on the wettest days.

0%10%20%30%151015202531
Rain chance (%)
112
212
311
411
511
611
711
811
911
1012
1112
1212
1312
1412
1512
1612
1712
1812
1912
2011
2111
2211
2310
249
259
268
278
287
297
306
316

Humidity in May

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, May lands in the dry band about 93% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)
1964
2973
3973
4973
5973
6964
7964
8964
9964
10955
11955
12955
13946
14946
15946
16937
17937
18937
19928
20928
21919
22919
23919
249010
259010
269010
278911
288911
298911
308812
318812

Wind in May

Winds average 6 mph in May, the windiest month of the year.

Across May, daily wind ranges from about 6 mph on the calmest days to 6 mph at its breeziest. It stays fairly steady from day to day.

0246810151015202531
Wind speed (mph)Feels
16calm
26calm
36calm
46calm
56calm
66calm
76calm
86calm
96calm
106calm
116calm
126calm
136calm
146calm
156calm
166calm
176calm
186calm
196calm
206calm
216calm
226calm
236calm
246calm
256calm
266calm
276calm
286calm
296calm
306calm
316calm

Sunrise & sunset in May

DaylightNight

Daylight runs from about 13 h 30 min at the start of May to 14 h 24 min by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 54 minutes over May. Sunrise moves from 5:20 AM to 4:55 AM, and sunset from 6:52 PM to 7:18 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
113.55:206:52
213.65:196:53
313.65:186:54
413.65:176:55
513.75:166:56
613.75:156:57
713.75:146:58
813.85:136:58
913.85:126:59
1013.85:117:00
1113.95:107:01
1213.95:097:02
1313.95:087:03
1414.05:077:04
1514.05:067:05
1614.05:057:06
1714.05:047:06
1814.15:037:07
1914.15:037:08
2014.15:027:09
2114.15:017:10
2214.25:007:11
2314.25:007:11
2414.24:597:12
2514.24:587:13
2614.34:587:14
2714.34:577:15
2814.34:577:15
2914.34:567:16
3014.44:567:17
3114.44:557:18

Solar energy in May

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in May, about 7.11 kWh/m².

For context, solar energy here swings from a low near 2.27 kWh/m² to a high of 7.76 kWh/m² in June across the year — May's 7.11 kWh/m² sits near the top of that range.

02468151015202531
Solar energy (kWh/m²)Level
16.8Intense
26.9Intense
36.9Intense
46.9Intense
56.9Intense
67.0Intense
77.0Intense
87.0Intense
97.0Intense
107.0Intense
117.0Intense
127.1Intense
137.1Intense
147.1Intense
157.1Intense
167.1Intense
177.1Intense
187.2Intense
197.2Intense
207.2Intense
217.2Intense
227.2Intense
237.2Intense
247.3Intense
257.3Intense
267.3Intense
277.3Intense
287.3Intense
297.4Intense
307.4Intense
317.4Intense
Planning a trip in May

Hazard calendar for San Carlos

In seasonPeak

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

San Carlos'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 May a good time to visit San Carlos?

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

7.4
Sightseeing
6th-best month of the year
3.3
Beach & pool
6th-best month of the year

May is one of the better times to visit San Carlos for general sightseeing.

What to pack for San Carlos in May

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

In May, San Carlos sees daytime highs around 66°F and nights near 52°F. Pack sun protection. About 3 days see rain.

sun protection

Sea temperature near San Carlos in May

The nearest coast averages about 54°F in May — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea at the nearest coast (about 11 mi away) is warmest in August at about 59°F and coldest in April near 54°F.

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

52°54°56°58°60°JanFebMarAprMayJunJulAugSepOctNovDecbracingcool
Sea temperature (°F)Comfort
Jan54Bracing
Feb54Bracing
Mar54Bracing
Apr54Bracing
May54Bracing
Jun55Bracing
Jul57Bracing
Aug59Bracing
Sep59Bracing
Oct58Bracing
Nov56Bracing
Dec55Bracing

UV index in San Carlos in May

LowModerateHighVery highExtreme

Clear-sky midday UV in May peaks around 8 (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 Carlos peaks around June 23 at about 10 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 15 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 15UV 2
UV index (midday)Level
Jan2Moderate
Feb4Moderate
Mar5Moderate
Apr6High
May8Very high
Jun10Extreme
Jul10Extreme
Aug10Very high
Sep6High
Oct5High
Nov2Moderate
Dec2Moderate

Air quality in San Carlos in May

GoodModeratePoorUnhealthyVery unhealthy

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

Air quality in San Carlos is worst in August — around 25 µg/m³ PM2.5 (moderate), about 2.5× the cleanest month (June, 10 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecModerateGoodModerateAug 1824 µg/m³Jun 1110 µg/m³
PM2.5 (µg/m³)Level
Jan15Moderate
Feb18Moderate
Mar16Moderate
Apr12Moderate
May10Good
Jun10Good
Jul11Good
Aug25Moderate
Sep17Moderate
Oct20Moderate
Nov18Moderate
Dec13Moderate
Location & terrain

Where is San Carlos?

San Carlos sits at 37.5°N, 122.3°W, 33 ft above sea level, in United States. The nearest listed city is Belmont, 1.2 mi away.

Topography around San Carlos

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

Within 2 miles, the terrain around San Carlos has significant variations in elevation — a maximum elevation change of 902 ft around an average of 121 ft above sea level; within 10 miles, large variations in elevation — a maximum elevation change of 2,454 ft; within 50 miles, very significant variations in elevation — a maximum elevation change of 4,452 ft.

The land around San Carlos is covered by artificial surfaces (50%) and trees (27%) within 2 miles, trees (39%) and water (33%) within 10 miles, and water (40%), trees (24%) and grassland (21%) within 50 miles.

2 miles
902 ft
10 miles
2,454 ft
50 miles
4,452 ft
treesshrubsgrasslandcroplandartificial surfacesbare terrainwaterwetland
May weather nearby: Belmont 1.2 mi · Redwood City 1.9 mi · Foster City 3.7 mi · San Mateo 5.0 mi · Menlo Park 5.6 mi · East Palo Alto 6.8 mi · Burlingame 8.1 mi · Palo Alto 8.1 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 San Carlos (37.5072°, -122.2605°, elevation 33 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).