San Rafael weather in May

In May, San Rafael sees average daytime highs of 67°F and overnight lows near 52°F, with 0.8 in of rain across 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 67°F through the month. The sky is clear or mostly clear about 57% of the time in May, and the air most often feels dry.

Daylight stretches from about 13 h 36 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 Rafael's 6th-clearest and 1st-windiest month. For the whole year in context, see San Rafael's year-round climate.

Daytime high
67°
6th warmest
Overnight low
52°
7th coldest
Rainfall
0.8 in
3 wet days
Daylight
14 hours
5:05 AM – 7:08 PM
Cloud cover
39%
6th clearest
Wind
9 mph
1st windiest
Solar energy
7.12 kWh/m²
Travel score
7.6
out of 10

San Rafael is city and the county seat of Marin County, California, United States.

Density
1,019/km²
people per km²
Founded
1874

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 67°F through the month.

A typical May day in San Rafael reaches about 67°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 60°F and 75°F. Set against its neighbours, May runs about 4°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
126751
136752
146752
156752
166752
176752
186752
196752
206752
216752
226752
236752
246753
256853
266853
276853
286853
296853
306853
316953

San Rafael 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
Jan56° / 44°4.59.99.73.9
Feb58° / 46°4.7910.54.4
Mar61° / 48°3.48.811.75.2
Apr63° / 49°1.54.9136.5
May67° / 52°0.83147.6
Jun71° / 54°0.20.814.68.6
Jul72° / 55°0.00.114.48.9
Aug73° / 56°0.00.213.59.0
Sep73° / 55°0.10.412.39.0
Oct70° / 53°1.02.9118.1
Nov62° / 48°2.269.95.9
Dec56° / 44°4.49.89.43.9

Cloud cover in May

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 57% of the time in May.

Beyond those clear spells, partly cloudy skies cover about 16% of May, with mostly cloudy or overcast conditions the remaining 27%. Skies tend to open up as the month goes on.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
16832
26832
36931
46931
56931
66931
76931
86931
96931
106931
117030
127030
137129
147228
157228
167228
177327
187327
197426
207426
217525
227624
237624
247624
257822
267822
277822
287921
297921
307822
317822

Chance of precipitation in May

Any precipitation

San Rafael gets around 0.8 in of rain over 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 9% and peaks near 11% on the wettest days.

0%10%20%30%151015202531
Rain chance (%)
111
211
311
411
511
611
711
811
911
1011
1111
1210
1310
1410
1510
1610
1710
1810
1910
209
219
229
238
248
258
267
277
286
296
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 96% 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
7982
8982
9982
10982
11973
12973
13973
14973
15964
16964
17964
18964
19964
20955
21955
22955
23955
24955
25955
26955
27955
28946
29946
30946
31946

Wind in May

Winds average 9 mph in May, the windiest month of the year.

Across May, daily wind ranges from about 8 mph on the calmest days to 9 mph at its breeziest. It stays fairly steady from day to day.

051015151015202531
Wind speed (mph)Feels
18light breeze
28light breeze
38light breeze
48light breeze
58light breeze
68light breeze
78light breeze
88light breeze
99light breeze
109light breeze
119light breeze
129light breeze
139light breeze
149light breeze
159light breeze
169light breeze
179light breeze
189light breeze
199light breeze
209light breeze
219light breeze
229light breeze
239light breeze
249light breeze
259light breeze
269light breeze
279light breeze
289light breeze
299light breeze
309light breeze
319light breeze

Sunrise & sunset in May

DaylightNight

Daylight runs from about 13 h 36 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 48 minutes over May. Sunrise moves from 5:21 AM to 4:55 AM, and sunset from 6:54 PM to 7:20 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
113.65:216:54
213.65:206:55
313.65:186:56
413.75:176:57
513.75:166:58
613.75:156:59
713.85:147:00
813.85:137:00
913.85:127:01
1013.95:117:02
1113.95:107:03
1213.95:097:04
1314.05:087:05
1414.05:077:06
1514.05:067:07
1614.05:057:08
1714.15:047:09
1814.15:037:09
1914.15:037:10
2014.25:027:11
2114.25:017:12
2214.25:007:13
2314.25:007:14
2414.34:597:15
2514.34:587:15
2614.34:587:16
2714.34:577:17
2814.44:577:18
2914.44:567:18
3014.44:567:19
3114.44:557:20

Solar energy in May

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in May, about 7.12 kWh/m².

For context, solar energy here swings from a low near 2.13 kWh/m² to a high of 7.85 kWh/m² in June across the year — May's 7.12 kWh/m² sits near the top of that range.

02468151015202531
Solar energy (kWh/m²)Level
16.8Intense
26.8Intense
36.9Intense
46.9Intense
56.9Intense
66.9Intense
77.0Intense
87.0Intense
97.0Intense
107.0Intense
117.0Intense
127.1Intense
137.1Intense
147.1Intense
157.1Intense
167.1Intense
177.2Intense
187.2Intense
197.2Intense
207.2Intense
217.2Intense
227.3Intense
237.3Intense
247.3Intense
257.3Intense
267.3Intense
277.4Intense
287.4Intense
297.4Intense
307.5Intense
317.5Intense
Planning a trip in May

Hazard calendar for San Rafael

In seasonPeak

None of San Rafael'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 Rafael'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 Rafael?

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

7.6
Sightseeing
6th-best month of the year
3.6
Beach & pool
6th-best month of the year

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

What to pack for San Rafael in May

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

In May, San Rafael sees daytime highs around 67°F and nights near 52°F. Pack sun protection. About 3 days see rain.

sun protection

Sea temperature near San Rafael in May

The nearest coast averages about 53°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 9 mi away) is warmest in September at about 58°F and coldest in April near 53°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
Jan53Bracing
Feb53Bracing
Mar54Bracing
Apr53Bracing
May53Bracing
Jun54Bracing
Jul56Bracing
Aug58Bracing
Sep58Bracing
Oct57Bracing
Nov55Bracing
Dec54Bracing

UV index in San Rafael 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 Rafael peaks around July 11 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 highHighModerateJul 11UV 10Dec 15UV 2
UV index (midday)Level
Jan2Moderate
Feb4Moderate
Mar5Moderate
Apr6High
May8Very high
Jun10Extreme
Jul10Extreme
Aug10Very high
Sep6High
Oct5High
Nov2Moderate
Dec2Low

Air quality in San Rafael 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 Rafael is worst in September — around 29 µg/m³ PM2.5 (moderate), about 4.2× the cleanest month (June, 7 µg/m³).

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

010203040JanFebMarAprMayJunJulAugSepOctNovDecModerateGoodModerateSep 1829 µg/m³Jun 127 µg/m³
PM2.5 (µg/m³)Level
Jan13Moderate
Feb13Moderate
Mar13Moderate
Apr10Good
May8Good
Jun7Good
Jul10Good
Aug25Moderate
Sep29Moderate
Oct27Moderate
Nov16Moderate
Dec12Good
Location & terrain

Where is San Rafael?

San Rafael sits at 38.0°N, 122.5°W, 43 ft above sea level, in United States. The nearest listed city is Novato, 9.3 mi away.

Topography around San Rafael

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

Within 2 miles, the terrain around San Rafael has significant variations in elevation — a maximum elevation change of 994 ft around an average of 174 ft above sea level; within 10 miles, large variations in elevation — a maximum elevation change of 2,808 ft; within 50 miles, very significant variations in elevation — a maximum elevation change of 4,459 ft.

The land around San Rafael is covered by trees (62%) and artificial surfaces (31%) within 2 miles, trees (42%) and water (36%) within 10 miles, and water (40%), trees (23%) and grassland (22%) within 50 miles.

2 miles
994 ft
10 miles
2,808 ft
50 miles
4,459 ft
treesgrasslandcroplandartificial surfaceswaterwetland
May weather nearby: Novato 9.3 mi · San Pablo 9.9 mi · Richmond 11 mi · El Cerrito 12 mi · Pinole 13 mi · Hercules 14 mi · Chinatown 14 mi · Albany 14 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 Rafael (37.9735°, -122.5311°, elevation 43 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).