Napa weather in May

In May, Napa sees average daytime highs of 76°F and overnight lows near 52°F, with 0.8 in of rain across 3.2 wet days and about 14 hours of daylight. It is the 6th-warmest and 8th-wettest month of the year here.

Highs climb over the month, from about 74°F in the first days to 78°F by the end. The sky is clear or mostly clear about 56% 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 Napa's 6th-clearest and 3rd-windiest month. For the whole year in context, see Napa's year-round climate.

Daytime high
76°
6th warmest
Overnight low
52°
8th coldest
Rainfall
0.8 in
3.2 wet days
Daylight
14 h 06 min
5:03 AM – 7:07 PM
Cloud cover
37%
6th clearest
Wind
6 mph
3rd windiest
Solar energy
7.21 kWh/m²
Travel score
8.4
out of 10

Napa is city in Napa County, California, United States.

Density
1,721/km²
people per km²
Founded
1872

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

Temperature in May

Average highAverage lowShaded bands: 10–90% of days

Highs climb over the month, from about 74°F in the first days to 78°F by the end.

A typical May day in Napa reaches about 76°F in the afternoon and slips back to 52°F overnight — a 23°F spread between the day's warmth and the night's chill. On most days the high lands between 65°F and 87°F. Set against its neighbours, May runs about 6°F warmer than April and about 6°F cooler than June.

40°60°80°151015202531
Avg high (°F)Avg low (°F)
17451
27451
37451
47451
57451
67451
77451
87451
97552
107552
117552
127552
137552
147552
157552
167552
177552
187653
197653
207653
217653
227653
237653
247753
257753
267754
277754
287854
297854
307854
317854

Napa 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
Jan58° / 42°4.69.49.64.3
Feb61° / 44°4.68.610.55.1
Mar65° / 46°3.48.411.76.2
Apr69° / 48°1.54.9137.4
May76° / 52°0.83.2148.4
Jun82° / 56°0.20.914.68.1
Jul84° / 57°0.00.114.47.6
Aug84° / 57°0.00.213.57.5
Sep83° / 56°0.10.412.38.0
Oct76° / 52°1.02.9118.5
Nov65° / 46°2.25.99.96.5
Dec57° / 42°4.39.39.44.3

Cloud cover in May

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 56% of the time in May.

Beyond those clear spells, partly cloudy skies cover about 15% of May, with mostly cloudy or overcast conditions the remaining 28%. Skies tend to open up as the month goes on.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
16535
26634
36634
46733
56832
66832
76832
86832
96832
106832
116931
126931
137030
147129
157129
167228
177228
187327
197327
207426
217525
227525
237525
247723
257723
267723
277723
287723
297822
307822
317822

Chance of precipitation in May

Any precipitation

Napa gets around 0.8 in of rain over 3.2 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 13% on the wettest days. The odds ease toward the end of the month.

0%10%20%30%151015202531
Rain chance (%)
113
213
312
412
512
612
712
812
912
1012
1112
1211
1311
1411
1511
1611
1710
1810
1910
2010
219
229
239
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 (%)
1973
2973
3982
4982
5982
6982
7973
8973
9973
10973
11973
12973
13973
14973
15973
16964
17964
18964
19964
20955
21955
22955
23946
24946
25946
26937
27937
28937
29928
30928
31928

Wind in May

Winds average 6 mph in May.

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 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 5:19 AM to 4:53 AM, and sunset from 6:53 PM to 7:20 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
113.65:196:53
213.65:186:54
313.65:176:55
413.75:166:56
513.75:146:57
613.75:136:58
713.85:126:59
813.85:117:00
913.95:107:01
1013.95:097:02
1113.95:087:03
1213.95:077:04
1314.05:067:05
1414.05:057:06
1514.05:047:07
1614.15:037:07
1714.15:027:08
1814.15:027:09
1914.25:017:10
2014.25:007:11
2114.24:597:12
2214.24:597:13
2314.34:587:14
2414.34:577:14
2514.34:567:15
2614.34:567:16
2714.44:557:17
2814.44:557:18
2914.44:547:18
3014.44:547:19
3114.44:537:20

Solar energy in May

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in May, about 7.21 kWh/m².

For context, solar energy here swings from a low near 2.08 kWh/m² to a high of 8.05 kWh/m² in July across the year — May's 7.21 kWh/m² falls in the middle.

02468151015202531
Solar energy (kWh/m²)Level
16.8Intense
26.9Intense
36.9Intense
46.9Intense
57.0Intense
67.0Intense
77.0Intense
87.0Intense
97.1Intense
107.1Intense
117.1Intense
127.1Intense
137.2Intense
147.2Intense
157.2Intense
167.2Intense
177.2Intense
187.3Intense
197.3Intense
207.3Intense
217.3Intense
227.4Intense
237.4Intense
247.4Intense
257.4Intense
267.5Intense
277.5Intense
287.5Intense
297.6Intense
307.6Intense
317.6Intense
Planning a trip in May

Hazard calendar for Napa

In seasonPeak

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

Napa'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 Napa?

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

8.4
Sightseeing
2nd-best month of the year
7.2
Beach & pool
6th-best month of the year

May is one of the better times to visit Napa for general sightseeing. The water and warmth also suit a beach or pool day.

What to pack for Napa in May

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

In May, Napa sees daytime highs around 76°F and nights near 52°F. Pack sun protection. Worth having: light clothes. About 3 days see rain.

sun protectionlight clothes

Sea temperature near Napa 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 35 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 Napa in May

LowModerateHighVery highExtreme

Clear-sky midday UV in May peaks around 9 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Napa peaks around June 23 at about 10 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 13 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 13UV 2
UV index (midday)Level
Jan2Moderate
Feb4Moderate
Mar5Moderate
Apr6High
May9Very high
Jun10Extreme
Jul10Extreme
Aug9Very high
Sep6High
Oct5High
Nov2Moderate
Dec2Low

Air quality in Napa 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 Napa 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 Napa?

Napa sits at 38.3°N, 122.3°W, 20 ft above sea level, in United States. The nearest listed city is American Canyon, 8.7 mi away.

Topography around Napa

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

Within 2 miles, the terrain around Napa has only modest variations in elevation — a maximum elevation change of 492 ft around an average of 79 ft above sea level; within 10 miles, large variations in elevation — a maximum elevation change of 2,585 ft; within 50 miles, very significant variations in elevation — a maximum elevation change of 4,895 ft.

The land around Napa is covered by artificial surfaces (45%) and trees (33%) within 2 miles, trees (38%) and grassland (38%) within 10 miles, and trees (29%) and grassland (29%) within 50 miles.

2 miles
492 ft
10 miles
2,585 ft
50 miles
4,895 ft
treesshrubsgrasslandcroplandartificial surfaceswaterwetland
May weather nearby: American Canyon 8.7 mi · Agua Caliente 11 mi · Vallejo 14 mi · Fairfield 14 mi · Suisun 14 mi · Vacaville 17 mi · Benicia 19 mi · Hercules 19 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 Napa (38.2971°, -122.2855°, elevation 20 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).