Seaside weather in September

In September, Seaside sees average daytime highs of 70°F and overnight lows near 53°F, with 0.1 in of rain across 0.6 wet days and about 12.2 hours of daylight. It is the 2nd-warmest and 10th-wettest month of the year here.

Day-to-day highs hold fairly steady near 70°F through the month. The sky is clear or mostly clear about 84% of the time in September, and the air most often feels dry.

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 Seaside's 1st-clearest and 12th-windiest month. For the whole year in context, see Seaside's year-round climate.

Daytime high
70°
2nd warmest
Overnight low
53°
11th coldest
Rainfall
0.1 in
0.6 wet days
Daylight
12 h 12 min
5:55 AM – 6:09 PM
Cloud cover
20%
1st clearest
Wind
4 mph
12th windiest
Solar energy
6.05 kWh/m²
Travel score
8.7
out of 10

Seaside is city in Monterey County, California, United States.

Density
1,360/km²
people per km²
Founded
1954

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 70°F through the month.

A typical September day in Seaside reaches about 70°F in the afternoon and slips back to 53°F overnight — a 17°F spread between the day's warmth and the night's chill. On most days the high lands between 64°F and 78°F. Set against its neighbours, September runs on par with August and about 3°F warmer than October.

40°50°60°70°80°151015202530
Avg high (°F)Avg low (°F)
17154
27154
37154
47154
57154
67154
77054
87054
97054
107053
117053
127053
137053
147053
157053
167053
177053
187053
197053
207053
217053
227053
237053
247053
257053
267053
277053
287053
296953
306953

Seaside weather by month

How September compares with the rest of the year at a glance. September is the 2nd-warmest and 10th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysDaylight (hours)Travel score
Jan56° / 44°4.29.19.84.0
Feb57° / 44°4.29.610.64.0
Mar58° / 45°3.39.111.74.5
Apr59° / 46°1.55.512.95.3
May62° / 48°0.62.913.96.6
Jun66° / 50°0.10.614.58.1
Jul70° / 53°0.00.214.28.7
Aug71° / 54°0.10.213.48.8
Sep70° / 53°0.10.612.28.7
Oct67° / 51°0.92.511.17.9
Nov61° / 46°1.95.8105.7
Dec56° / 43°3.88.59.54.0

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 84% of the time in September, the clearest month of the year.

Beyond those clear spells, partly cloudy skies cover about 8% 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 (%)
1964
2964
3964
4955
5955
6955
7955
8955
9955
10946
11937
12937
13937
14937
15937
16937
17937
18919
19919
20919
21919
22919
239010
249010
259010
269010
278911
288911
298911
308911

Chance of precipitation in September

Any precipitation

Seaside gets around 0.1 in of rain over 0.6 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 3% on the wettest days.

0%10%20%30%151015202530
Rain chance (%)
11
21
31
41
51
62
72
82
92
102
112
122
132
142
152
162
172
182
192
202
212
222
232
242
252
263
273
283
293
303

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, September lands in the dry band about 88% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)
182162
283152
383152
484142
584142
685132
785132
886122
986122
1088111
1188111
1288111
1388111
1488111
1588111
1689110
1789110
1889110
1989110
2089110
2189110
2289110
2389110
2489110
2589110
2690100
2790100
289190
299280
309280

Wind in September

Winds average 4 mph in September, the calmest month.

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 5:43 AM to 6:07 AM, and sunset from 6:32 PM to 5:47 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.85:436:32
212.85:436:30
312.75:446:29
412.75:456:27
512.75:466:26
612.65:476:24
712.65:476:23
812.55:486:21
912.55:496:20
1012.55:506:18
1112.45:516:16
1212.45:526:15
1312.35:526:13
1412.35:536:12
1512.35:546:10
1612.25:556:09
1712.25:566:07
1812.15:566:05
1912.15:576:04
2012.15:586:02
2112.05:596:01
2212.06:005:59
2312.06:015:58
2411.96:015:56
2511.96:025:55
2611.86:035:53
2711.86:045:51
2811.86:055:50
2911.76:065:48
3011.76:075:47

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 6.05 kWh/m².

For context, solar energy here swings from a low near 2.53 kWh/m² to a high of 8.03 kWh/m² in June across the year — September's 6.05 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
16.7Intense
26.7Intense
36.6Intense
46.6Intense
56.5Intense
66.5Intense
76.4Intense
86.4Intense
96.3Intense
106.3Intense
116.3Intense
126.2Intense
136.2Intense
146.1Intense
156.1Intense
166.0Intense
176.0Bright
185.9Bright
195.9Bright
205.8Bright
215.8Bright
225.7Bright
235.7Bright
245.6Bright
255.6Bright
265.5Bright
275.5Bright
285.4Bright
295.4Bright
305.3Bright
Planning a trip in September

Hazard calendar for Seaside

In seasonPeak

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

Seaside'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 Seaside?

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

8.7
Sightseeing
2nd-best month of the year
5.4
Beach & pool
2nd-best month of the year

September is one of the better times to visit Seaside for general sightseeing.

What to pack for Seaside in September

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

In September, Seaside sees daytime highs around 70°F and nights near 53°F. Pack sun protection.

sun protection

Sea temperature near Seaside 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
Nov57Bracing
Dec55Bracing

UV index in Seaside in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 6 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Seaside 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
Jan3Moderate
Feb4Moderate
Mar5Moderate
Apr7High
May8Very high
Jun10Extreme
Jul10Extreme
Aug10Very high
Sep6High
Oct5High
Nov2Moderate
Dec2Moderate

Air quality in Seaside 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 Seaside 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 Seaside?

Seaside sits at 36.6°N, 121.9°W, 23 ft above sea level, in United States. The nearest listed city is Monterey, 2.5 mi away.

Topography around Seaside

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

Within 2 miles, the terrain around Seaside has only modest variations in elevation — a maximum elevation change of 417 ft around an average of 89 ft above sea level; within 10 miles, large variations in elevation — a maximum elevation change of 2,218 ft; within 50 miles, very significant variations in elevation — a maximum elevation change of 5,883 ft.

The land around Seaside is covered by artificial surfaces (39%) and water (36%) within 2 miles, water (39%) and trees (31%) within 10 miles, and water (33%), trees (28%) and grassland (27%) within 50 miles.

2 miles
417 ft
10 miles
2,218 ft
50 miles
5,883 ft
treesshrubsgrasslandcroplandartificial surfacesbare terrainwater
September weather nearby: Monterey 2.5 mi · Pacific Grove 3.7 mi · Marina 5.6 mi · Salinas 12 mi · Prunedale 15 mi · Watsonville 21 mi · Big Sur 24 mi · Live Oak 27 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 Seaside (36.6111°, -121.8516°, elevation 23 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).