Oceanside weather in September

In September, Oceanside sees average daytime highs of 75°F and overnight lows near 66°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 9th-wettest month of the year here.

Day-to-day highs hold fairly steady near 75°F through the month. The sky is clear or mostly clear about 79% of the time in September, and the air most often feels humid.

Daylight stretches from about 12 h 42 min at the start of September to 11 h 42 min by month's end. Set against the rest of the year, September is Oceanside's 2nd-clearest and 9th-windiest month. For the whole year in context, see Oceanside's year-round climate.

Daytime high
75°
2nd warmest
Overnight low
66°
11th coldest
Rainfall
0.1 in
0.6 wet days
Daylight
12 h 12 min
5:38 AM – 5:50 PM
Cloud cover
22%
2nd clearest
Wind
5 mph
9th windiest
Solar energy
6.05 kWh/m²
Travel score
9.3
out of 10

Oceanside is city in San Diego County, California, United States.

Density
1,608/km²
people per km²
Founded
1888

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 75°F through the month.

A typical September day in Oceanside reaches about 75°F in the afternoon and slips back to 66°F overnight — a 9°F spread between the day's warmth and the night's chill. On most days the high lands between 69°F and 82°F. Set against its neighbours, September runs on par with August and about 3°F warmer than October.

60°70°80°151015202530
Avg high (°F)Avg low (°F)
17667
27667
37667
47667
57667
67667
77667
87667
97667
107667
117567
127566
137566
147566
157566
167566
177566
187566
197566
207566
217566
227566
237565
247565
257465
267465
277465
287465
297465
307465

Oceanside weather by month

How September compares with the rest of the year at a glance. September is the 2nd-warmest and 9th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysDaylight (hours)Travel score
Jan62° / 52°2.55.310.16.2
Feb62° / 53°2.96.110.85.9
Mar63° / 54°1.65.311.76.3
Apr64° / 56°0.7312.87.2
May66° / 58°0.31.813.77.6
Jun69° / 62°0.10.414.28.4
Jul74° / 65°0.00.3149.2
Aug76° / 67°0.00.213.29.5
Sep75° / 66°0.10.612.29.3
Oct72° / 63°0.5211.28.5
Nov67° / 58°0.82.710.37.7
Dec63° / 53°1.84.79.86.5

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 79% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 9% of September, with mostly cloudy or overcast conditions the remaining 12%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
1919
2919
3919
4919
5919
6919
7919
8919
9919
10919
118911
128911
138911
148911
158911
168812
178812
188713
198713
208614
218614
228614
238614
248515
258416
268416
278416
288416
298416
308416

Chance of precipitation in September

Any precipitation

Oceanside 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
61
71
81
91
101
112
122
132
142
152
162
173
183
193
203
213
223
233
243
253
263
273
283
293
303

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, September lands in the humid band about 41% of days. Sticky, muggy-or-worse air turns up on roughly 39% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
10937477
201037467
301137457
401238447
501338437
601438416
701539406
801639396
901740385
1001741375
1101841364
1211942354
1312042344
1412042333
1512143323
1612143323
1712143313
1822243313
1922143313
2022143313
2122143313
2232143312
2332142312
2432242312
2542241302
2642341302
2752440292
2862540282
2962640271
3072739261

Wind in September

Winds average 5 mph in September.

Across September, daily wind ranges from about 5 mph on the calmest days to 5 mph at its breeziest. It stays fairly steady from day to day.

0246810151015202530
Wind speed (mph)Feels
15calm
25calm
35calm
45calm
55calm
65calm
75calm
85calm
95calm
105calm
115calm
125calm
135calm
145calm
155calm
165calm
175calm
185calm
195calm
205calm
215calm
225calm
235calm
245calm
255calm
265calm
275calm
285calm
295calm
305calm

Sunrise & sunset in September

DaylightNight

Daylight runs from about 12 h 42 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 60 minutes over September. Sunrise moves from 5:28 AM to 5:48 AM, and sunset from 6:11 PM to 5:30 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.75:286:11
212.75:286:10
312.75:296:08
412.65:306:07
512.65:306:05
612.65:316:04
712.55:326:03
812.55:326:01
912.45:336:00
1012.45:345:58
1112.45:345:57
1212.35:355:56
1312.35:365:54
1412.35:365:53
1512.25:375:51
1612.25:385:50
1712.25:385:48
1812.15:395:47
1912.15:405:46
2012.15:415:44
2112.05:415:43
2212.05:425:41
2312.05:435:40
2411.95:435:39
2511.95:445:37
2611.95:455:36
2711.85:455:34
2811.85:465:33
2911.75:475:32
3011.75:485:30

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 3.05 kWh/m² to a high of 7.71 kWh/m² in June across the year — September's 6.05 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
16.6Intense
26.6Intense
36.5Intense
46.5Intense
56.5Intense
66.4Intense
76.4Intense
86.4Intense
96.3Intense
106.3Intense
116.2Intense
126.2Intense
136.2Intense
146.1Intense
156.1Intense
166.0Intense
176.0Intense
186.0Bright
195.9Bright
205.9Bright
215.8Bright
225.8Bright
235.7Bright
245.7Bright
255.7Bright
265.6Bright
275.6Bright
285.5Bright
295.5Bright
305.4Bright
Planning a trip in September

Is September a good time to visit Oceanside?

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
7.7
Beach & pool
2nd-best month of the year

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

What to pack for Oceanside in September

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

In September, Oceanside sees daytime highs around 75°F and nights near 66°F. Pack sun protection. Worth having: light clothes.

sun protectionlight clothes

Sea temperature near Oceanside in September

The nearest coast averages about 70°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 August at about 71°F and coldest in January near 59°F.

It's comfortable for a long swim from Jul 5 to Oct 7 — about 3.1 months when the water holds above 68°F.

60°65°70°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingcomfortable to swim
Sea temperature (°F)Comfort
Jan59Cool
Feb59Cool
Mar60Cool
Apr61Cool
May64Cool
Jun66Cool
Jul69Refreshing
Aug71Refreshing
Sep70Refreshing
Oct67Cool
Nov64Cool
Dec61Cool

UV index in Oceanside in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September 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 Oceanside peaks around July 11 at about 11 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 17 at about 3 (moderate).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 11 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateVery highExtremeVery highHighModerateJul 11UV 11Dec 17UV 3
UV index (midday)Level
Jan4Moderate
Feb5Moderate
Mar5Moderate
Apr8Very high
May8Very high
Jun11Extreme
Jul11Extreme
Aug10Extreme
Sep8Very high
Oct6High
Nov4Moderate
Dec3Moderate

Air quality in Oceanside 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 Oceanside is worst in September — around 24 µg/m³ PM2.5 (moderate), about 3.5× the cleanest month (May, 7 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodSep 1223 µg/m³May 207 µg/m³
PM2.5 (µg/m³)Level
Jan10Good
Feb11Good
Mar11Good
Apr10Good
May7Good
Jun8Good
Jul9Good
Aug20Moderate
Sep24Moderate
Oct12Moderate
Nov11Good
Dec11Good
Location & terrain

Where is Oceanside?

Oceanside sits at 33.2°N, 117.4°W, 66 ft above sea level, in United States. The nearest listed city is Carlsbad, 3.1 mi away.

Topography around Oceanside

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

Within 2 miles, the terrain around Oceanside has only modest variations in elevation — a maximum elevation change of 279 ft around an average of 59 ft above sea level; within 10 miles, significant variations in elevation — a maximum elevation change of 1,060 ft; within 50 miles, very significant variations in elevation — a maximum elevation change of 6,772 ft.

The land around Oceanside is covered by water (42%) and artificial surfaces (39%) within 2 miles, water (47%) within 10 miles, and water (33%) and shrubs (20%) within 50 miles.

2 miles
279 ft
10 miles
1,060 ft
50 miles
6,772 ft
treesshrubsgrasslandcroplandartificial surfacesbare terrainwater
September weather nearby: Carlsbad 3.1 mi · Vista 8.1 mi · Encinitas 12 mi · San Marcos 13 mi · Fallbrook 14 mi · Escondido 18 mi · San Clemente 21 mi · Rancho Penasquitos 22 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 Oceanside (33.1959°, -117.3795°, elevation 66 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).