Placentia weather in September

In September, Placentia sees average daytime highs of 81°F and overnight lows near 64°F, with 0.2 in of rain across 0.8 wet days and about 12.2 hours of daylight. It is the 2nd-warmest and 9th-wettest month of the year here.

Highs ease over the month, from about 83°F in the first days to 80°F by the end. The sky is clear or mostly clear about 86% 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 Placentia's 2nd-clearest and 11th-windiest month. For the whole year in context, see Placentia's year-round climate.

Daytime high
81°
2nd warmest
Overnight low
64°
10th coldest
Rainfall
0.2 in
0.8 wet days
Daylight
12 h 12 min
5:40 AM – 5:52 PM
Cloud cover
16%
2nd clearest
Wind
4 mph
11th windiest
Solar energy
6.12 kWh/m²
Travel score
8.6
out of 10

Placentia is city in Orange County, California, United States.

Density
3,079/km²
people per km²
Founded
1926

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

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 83°F in the first days to 80°F by the end.

A typical September day in Placentia reaches about 81°F in the afternoon and slips back to 64°F overnight — a 18°F spread between the day's warmth and the night's chill. On most days the high lands between 73°F and 89°F. Set against its neighbours, September runs about 1°F cooler than August and about 5°F warmer than October.

50°60°70°80°90°151015202530
Avg high (°F)Avg low (°F)
18365
28365
38365
48365
58365
68265
78265
88265
98265
108264
118264
128164
138164
148164
158164
168163
178163
188163
198063
208063
218063
228063
238063
248062
258062
268062
278062
288062
298062
308062

Placentia 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
Jan64° / 47°3.15.7106.7
Feb64° / 48°3.66.410.76.5
Mar66° / 51°2.2611.76.9
Apr69° / 53°0.93.112.87.8
May71° / 57°0.41.713.78.4
Jun76° / 60°0.10.314.29.2
Jul81° / 64°0.10.5148.8
Aug83° / 65°0.00.213.38.3
Sep81° / 64°0.20.812.28.6
Oct76° / 59°0.72.211.18.8
Nov70° / 52°0.92.610.28.1
Dec64° / 47°2.259.86.7

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 (%)
1946
2937
3937
4937
5937
6937
7937
8937
9937
10937
11937
12937
13937
14928
15928
16928
17928
18928
19928
20928
21919
22919
239010
249010
259010
269010
278911
288911
298911
308911

Chance of precipitation in September

Any precipitation

Placentia gets around 0.2 in of rain over 0.8 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 3% and peaks near 4% on the wettest days.

0%10%20%30%151015202530
Rain chance (%)
12
22
32
42
52
62
72
82
92
102
112
122
132
142
152
162
173
183
193
203
213
223
233
243
253
264
274
284
294
304

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 42% of days. Sticky, muggy-or-worse air turns up on roughly 9% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)
12315215
22325016
33324916
43334816
53354715
63364615
74374514
84384414
94394413
105404412
115404311
126414310
13642439
14742429
15743428
16843418
17943417
18943417
191043417
201042416
211142416
221242406
231342406
241342395
251442385
261643375
271743364
281843344
292043334
302243313

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 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 5:29 AM to 5:50 AM, and sunset from 6:13 PM to 5:32 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.75:296:13
212.75:306:12
312.75:306:11
412.65:316:09
512.65:326:08
612.65:336:06
712.55:336:05
812.55:346:04
912.55:356:02
1012.45:356:01
1112.45:365:59
1212.45:375:58
1312.35:375:56
1412.35:385:55
1512.25:395:53
1612.25:405:52
1712.25:405:51
1812.15:415:49
1912.15:425:48
2012.15:425:46
2112.05:435:45
2212.05:445:43
2312.05:455:42
2411.95:455:40
2511.95:465:39
2611.85:475:38
2711.85:475:36
2811.85:485:35
2911.75:495:33
3011.75:505:32

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 6.12 kWh/m².

For context, solar energy here swings from a low near 2.97 kWh/m² to a high of 7.88 kWh/m² in June across the year — September's 6.12 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
16.8Intense
26.7Intense
36.7Intense
46.6Intense
56.6Intense
66.5Intense
76.5Intense
86.5Intense
96.4Intense
106.4Intense
116.3Intense
126.3Intense
136.2Intense
146.2Intense
156.2Intense
166.1Intense
176.1Intense
186.0Intense
196.0Bright
205.9Bright
215.9Bright
225.8Bright
235.8Bright
245.7Bright
255.7Bright
265.7Bright
275.6Bright
285.6Bright
295.5Bright
305.5Bright
Planning a trip in September

Is September a good time to visit Placentia?

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

8.6
Sightseeing
4th-best month of the year
8.9
Beach & pool
2nd-best month of the year

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

What to pack for Placentia in September

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

In September, Placentia sees daytime highs around 81°F and nights near 64°F. Pack light clothes and sun protection.

light clothessun protection

Sea temperature near Placentia in September

The nearest coast averages about 69°F in September — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea at the nearest coast (about 17 mi away) is warmest in August at about 69°F and coldest in February near 59°F.

It's comfortable for a long swim from Jul 13 to Sep 28 — about 2.6 months when the water holds above 68°F.

60°65°70°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingcomfortable to swim
Sea temperature (°F)Comfort
Jan59Cool
Feb59Cool
Mar59Cool
Apr60Cool
May63Cool
Jun65Cool
Jul68Refreshing
Aug69Refreshing
Sep69Refreshing
Oct67Cool
Nov64Cool
Dec60Cool

UV index in Placentia in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 8 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Placentia peaks around July 11 at about 11 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 16 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 16UV 3
UV index (midday)Level
Jan4Moderate
Feb5Moderate
Mar5Moderate
Apr8Very high
May8Very high
Jun11Extreme
Jul11Extreme
Aug10Extreme
Sep8Very high
Oct6High
Nov3Moderate
Dec3Moderate

Air quality in Placentia 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 Placentia is worst in September — around 49 µg/m³ PM2.5 (poor), about 4.0× the cleanest month (May, 12 µg/m³).

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

0204060JanFebMarAprMayJunJulAugSepOctNovDecModeratePoorModerateSep 1447 µg/m³May 1713 µg/m³
PM2.5 (µg/m³)Level
Jan18Moderate
Feb19Moderate
Mar19Moderate
Apr17Moderate
May12Moderate
Jun17Moderate
Jul19Moderate
Aug32Moderate
Sep49Poor
Oct21Moderate
Nov21Moderate
Dec18Moderate
Location & terrain

Where is Placentia?

Placentia sits at 33.9°N, 117.9°W, 272 ft above sea level, in United States. The nearest listed city is Fullerton, 3.1 mi away.

Topography around Placentia

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

Within 2 miles, the terrain around Placentia has only modest variations in elevation — a maximum elevation change of 272 ft around an average of 249 ft above sea level; within 10 miles, significant variations in elevation — a maximum elevation change of 1,703 ft; within 50 miles, extreme variations in elevation — a maximum elevation change of 10,010 ft.

The land around Placentia is covered by artificial surfaces (87%) within 2 miles, artificial surfaces (65%) within 10 miles, and water (27%) and artificial surfaces (25%) within 50 miles.

2 miles
272 ft
10 miles
1,703 ft
50 miles
10,010 ft
treesshrubsgrasslandcroplandartificial surfacesbare terrainwater
September weather nearby: Fullerton 3.1 mi · Yorba Linda 3.7 mi · Brea 3.7 mi · Anaheim 3.7 mi · Orange 6.2 mi · La Habra 6.2 mi · Buena Park 7.5 mi · Rowland Heights 7.5 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 Placentia (33.8722°, -117.8703°, elevation 272 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).