Watsonville weather in September

In September, Watsonville sees average daytime highs of 73°F and overnight lows near 56°F, with 0.1 in of rain across 0.5 wet days and about 12.3 hours of daylight. It is the 1st-warmest and 10th-wettest month of the year here.

Day-to-day highs hold fairly steady near 73°F through the month. The sky is clear or mostly clear about 86% of the time in September, and the air most often feels comfortable.

Daylight stretches from about 12 h 48 min at the start of September to 11 h 42 min by month's end. Set against the rest of the year, September is Watsonville's 3rd-clearest and 10th-windiest month. For the whole year in context, see Watsonville's year-round climate.

Daytime high
73°
1st warmest
Overnight low
56°
11th coldest
Rainfall
0.1 in
0.5 wet days
Daylight
12 h 12 min
5:54 AM – 6:08 PM
Cloud cover
16%
3rd clearest
Wind
4 mph
10th windiest
Solar energy
5.88 kWh/m²
Travel score
9.3
out of 10

Watsonville is city in Santa Cruz County, California, United States.

Density
3,052/km²
people per km²
Founded
1868

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

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near 73°F through the month.

A typical September day in Watsonville reaches about 73°F in the afternoon and slips back to 56°F overnight — a 18°F spread between the day's warmth and the night's chill. On most days the high lands between 66°F and 82°F. Set against its neighbours, September runs on par with August and about 3°F warmer than October.

50°60°70°80°151015202530
Avg high (°F)Avg low (°F)
17457
27457
37457
47456
57456
67456
77456
87456
97456
107356
117356
127356
137356
147356
157356
167356
177356
187356
197356
207355
217355
227355
237355
247355
257355
267355
277355
287355
297355
307355

Watsonville weather by month

How September compares with the rest of the year at a glance. September is the 1st-warmest and 10th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysDaylight (hours)Travel score
Jan58° / 43°4.28.79.84.6
Feb60° / 45°4.2910.64.9
Mar62° / 46°3.08.411.75.6
Apr64° / 48°1.34.712.96.6
May67° / 51°0.62.813.97.6
Jun70° / 53°0.10.614.58.7
Jul72° / 56°0.00.214.39.2
Aug73° / 57°0.00.213.49.4
Sep73° / 56°0.10.512.39.3
Oct71° / 52°0.82.1118.4
Nov64° / 46°1.85.3106.5
Dec58° / 43°3.88.69.54.6

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 86% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 6% of September, with mostly cloudy or overcast conditions the remaining 8%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
1955
2955
3955
4955
5955
6946
7946
8946
9946
10946
11946
12946
13937
14937
15937
16928
17928
18928
19928
20928
219010
229010
239010
249010
258911
268911
278911
288911
298812
308713

Chance of precipitation in September

Any precipitation

Watsonville gets around 0.1 in of rain over 0.5 wet days in September. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 2% and peaks near 4% on the wettest days.

0%10%20%30%151015202530
Rain chance (%)
11
21
31
41
51
61
71
81
91
101
111
121
131
142
152
162
172
182
193
203
213
223
233
243
253
263
273
283
294
304

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, September lands in the comfortable band about 49% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)
136577
236577
337567
438557
539547
640546
741536
842526
943516
1043525
1144515
1245514
1345514
1445514
1546513
1646513
1747503
1847503
1948503
2048492
2149492
2250482
2351472
2452462
2553452
2654442
2755432
2858411
2959401
3061381

Wind in September

Winds average 4 mph in September.

Across September, daily wind ranges from about 4 mph on the calmest days to 4 mph at its breeziest. It stays fairly steady from day to day.

0246810151015202530
Wind speed (mph)Feels
14calm
24calm
34calm
44calm
54calm
64calm
74calm
84calm
94calm
104calm
114calm
124calm
134calm
144calm
154calm
164calm
174calm
184calm
194calm
204calm
214calm
224calm
234calm
244calm
254calm
264calm
274calm
284calm
294calm
304calm

Sunrise & sunset in September

DaylightNight

Daylight runs from about 12 h 48 min at the start of September to 11 h 42 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 66 minutes over September. Sunrise moves from 5:42 AM to 6:06 AM, and sunset from 6:32 PM to 5:46 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.85:426:32
212.85:436:30
312.75:446:29
412.75:446:27
512.75:456:26
612.65:466:24
712.65:476:22
812.65:486:21
912.55:496:19
1012.55:496:18
1112.45:506:16
1212.45:516:15
1312.45:526:13
1412.35:536:11
1512.35:546:10
1612.25:546:08
1712.25:556:07
1812.25:566:05
1912.15:576:04
2012.15:586:02
2112.05:596:00
2212.05:595:59
2311.96:005:57
2411.96:015:56
2511.96:025:54
2611.86:035:53
2711.86:045:51
2811.76:055:49
2911.76:055:48
3011.76:065:46

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 5.88 kWh/m².

For context, solar energy here swings from a low near 2.39 kWh/m² to a high of 7.82 kWh/m² in June across the year — September's 5.88 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
16.5Intense
26.5Intense
36.5Intense
46.4Intense
56.4Intense
66.3Intense
76.3Intense
86.2Intense
96.2Intense
106.1Intense
116.1Intense
126.0Intense
136.0Bright
145.9Bright
155.9Bright
165.8Bright
175.8Bright
185.8Bright
195.7Bright
205.7Bright
215.6Bright
225.6Bright
235.5Bright
245.5Bright
255.4Bright
265.4Bright
275.3Bright
285.3Bright
295.2Bright
305.2Bright
Planning a trip in September

Hazard calendar for Watsonville

In seasonPeak

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

Watsonville's rainy season runs December–March, when most of the year's rain falls.

Rainy season
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec

Is September a good time to visit Watsonville?

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

9.3
Sightseeing
2nd-best month of the year
7.1
Beach & pool
2nd-best month of the year

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

What to pack for Watsonville in September

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

In September, Watsonville sees daytime highs around 73°F and nights near 56°F. Worth packing: light clothes and sun protection.

light clothessun protection

Sea temperature near Watsonville in September

The nearest coast averages about 58°F in September — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea offshore is warmest in September at about 58°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
Jan55Bracing
Feb55Bracing
Mar55Bracing
Apr54Bracing
May54Bracing
Jun55Bracing
Jul57Bracing
Aug58Bracing
Sep58Bracing
Oct58Bracing
Nov56Bracing
Dec55Bracing

UV index in Watsonville in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 7 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Watsonville peaks around June 22 at about 11 (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 22UV 11Dec 13UV 2
UV index (midday)Level
Jan3Moderate
Feb4Moderate
Mar5Moderate
Apr7High
May8Very high
Jun11Extreme
Jul10Extreme
Aug10Very high
Sep7High
Oct5High
Nov2Moderate
Dec2Moderate

Air quality in Watsonville in September

GoodModeratePoorUnhealthyVery unhealthy

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

Air quality in Watsonville is worst in August — around 22 µg/m³ PM2.5 (moderate), about 4.2× the cleanest month (June, 5 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodAug 1920 µg/m³Jun 135 µg/m³
PM2.5 (µg/m³)Level
Jan7Good
Feb8Good
Mar8Good
Apr7Good
May6Good
Jun5Good
Jul8Good
Aug22Moderate
Sep15Moderate
Oct12Moderate
Nov8Good
Dec7Good
Location & terrain

Where is Watsonville?

Watsonville sits at 36.9°N, 121.8°W, 33 ft above sea level, in United States. The nearest listed city is Prunedale, 11 mi away.

Topography around Watsonville

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

Within 2 miles, the terrain around Watsonville has only modest variations in elevation — a maximum elevation change of 131 ft around an average of 43 ft above sea level; within 10 miles, large variations in elevation — a maximum elevation change of 2,651 ft; within 50 miles, very significant variations in elevation — a maximum elevation change of 5,121 ft.

The land around Watsonville is covered by artificial surfaces (40%) and cropland (38%) within 2 miles, trees (43%) and water (21%) within 10 miles, and grassland (35%), trees (28%) and water (25%) within 50 miles.

2 miles
131 ft
10 miles
2,651 ft
50 miles
5,121 ft
treesshrubsgrasslandcroplandartificial surfacesbare terrainwaterwetland
September weather nearby: Prunedale 11 mi · Gilroy 12 mi · Live Oak 13 mi · Santa Cruz 16 mi · Marina 16 mi · Morgan Hill 16 mi · Salinas 17 mi · Hollister 20 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 Watsonville (36.9102°, -121.7569°, 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).