Imperial weather in September

In September, Imperial sees average daytime highs of 102°F and overnight lows near 75°F, with 0.4 in of rain across 1.4 wet days and about 12.2 hours of daylight. It is the 4th-warmest and 4th-wettest month of the year here.

Highs ease over the month, from about 105°F in the first days to 98°F by the end. The sky is clear or mostly clear about 88% of the time in September, and the air most often feels dry.

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 Imperial's 2nd-clearest and 10th-windiest month. For the whole year in context, see Imperial's year-round climate.

Daytime high
102°
4th warmest
Overnight low
75°
10th coldest
Rainfall
0.4 in
1.4 wet days
Daylight
12 h 12 min
5:31 AM – 5:43 PM
Cloud cover
14%
2nd clearest
Wind
4 mph
10th windiest
Solar energy
6.31 kWh/m²
Travel score
0.8
out of 10

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

Density
1,127/km²
people per km²
Founded
1904

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 105°F in the first days to 98°F by the end.

A typical September day in Imperial reaches about 102°F in the afternoon and slips back to 75°F overnight — a 27°F spread between the day's warmth and the night's chill. On most days the high lands between 95°F and 109°F. Set against its neighbours, September runs about 6°F cooler than August and about 11°F warmer than October.

60°80°100°151015202530
Avg high (°F)Avg low (°F)
110680
210680
310580
410579
510579
610579
710478
810478
910478
1010477
1110377
1210376
1310376
1410375
1510275
1610275
1710274
1810174
1910174
2010173
2110173
2210073
2310072
2410072
2510071
269971
279971
289870
299870
309869

How September really feels in Imperial

Once humidity and wind are folded in, September averages 30 days that feel above 90°F and 0 that feel at or below 32°F — the comfort signal a plain temperature reading hides.

Days feeling ≥ 90°F
30
15 feel dangerously hot (≥ 102°F)
Days feeling ≤ 32°F
0
wind chill below the day's low

The story in September is heat — humidity pushes the afternoon "feels like" well above the raw temperature.

Imperial weather by month

How September compares with the rest of the year at a glance. September is the 4th-warmest and 4th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysDaylight (hours)Travel score
Jan71° / 48°0.41.710.18.4
Feb75° / 50°0.5210.88.7
Mar82° / 54°0.31.111.87.9
Apr88° / 59°0.10.512.85.8
May96° / 66°0.00.213.73.1
Jun104° / 73°0.0014.10.4
Jul109° / 81°0.21.513.90.0
Aug108° / 82°0.32.513.20.0
Sep102° / 75°0.41.412.20.8
Oct91° / 64°0.20.711.24.8
Nov79° / 53°0.20.610.38.6
Dec70° / 47°0.41.59.98.2

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 88% 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 6%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
1937
2937
3937
4937
5937
6955
7955
8955
9955
10955
11955
12955
13955
14955
15955
16955
17946
18946
19946
20946
21946
22946
23937
24937
25937
26937
27937
28937
29937
30928

Chance of precipitation in September

Any precipitation

Imperial gets around 0.4 in of rain over 1.4 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 5% and peaks near 9% on the wettest days.

0%10%20%30%151015202530
Rain chance (%)
19
29
38
48
58
67
77
86
96
106
115
125
135
144
154
164
174
184
194
203
213
223
233
243
253
263
273
283
292
302

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 61% of days. Sticky, muggy-or-worse air turns up on roughly 16% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)Miserable (%)
140121620101
241121620101
342111620101
44311161991
54511161991
64611161891
74711161780
84911161680
95211151480
105411151370
115611141270
125811141160
136011131060
14621113950
15641112850
16661111840
17671111740
18691110730
19691210630
20701210620
2171129620
2272119620
2373118610
2474118610
2574118610
2674118610
2776107610
2876107610
2978107500
307997500

Wind in September

Winds average 4 mph in September.

Across September, daily wind ranges from about 4 mph on the calmest days to 5 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
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 5:21 AM to 5:40 AM, and sunset from 6:03 PM to 5:23 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.75:216:03
212.75:216:02
312.65:226:01
412.65:235:59
512.65:235:58
612.55:245:57
712.55:255:55
812.55:255:54
912.45:265:52
1012.45:275:51
1112.45:275:50
1212.35:285:48
1312.35:295:47
1412.35:295:45
1512.25:305:44
1612.25:315:43
1712.25:315:41
1812.15:325:40
1912.15:335:38
2012.15:335:37
2112.05:345:36
2212.05:355:34
2312.05:355:33
2411.95:365:31
2511.95:375:30
2611.95:375:29
2711.85:385:27
2811.85:395:26
2911.75:395:24
3011.75:405:23

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 6.31 kWh/m².

For context, solar energy here swings from a low near 3.33 kWh/m² to a high of 8.52 kWh/m² in June across the year — September's 6.31 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
16.7Intense
26.6Intense
36.6Intense
46.6Intense
56.5Intense
66.5Intense
76.5Intense
86.5Intense
96.5Intense
106.5Intense
116.4Intense
126.4Intense
136.4Intense
146.4Intense
156.4Intense
166.3Intense
176.3Intense
186.3Intense
196.3Intense
206.2Intense
216.2Intense
226.2Intense
236.1Intense
246.1Intense
256.0Intense
266.0Intense
276.0Bright
286.0Bright
295.9Bright
305.9Bright
Planning a trip in September

Is September a good time to visit Imperial?

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

0.8
Sightseeing
9th-best month of the year
4.1
Beach & pool
9th-best month of the year

September is a weaker month for outdoor sightseeing in Imperial.

What to pack for Imperial in September

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

In September, Imperial sees daytime highs around 102°F and nights near 75°F. Pack light clothes and sun protection.

light clothessun protection

UV index in Imperial 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 Imperial peaks around June 21 at about 11 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 18 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 highHighModerateJun 21UV 11Dec 18UV 3
UV index (midday)Level
Jan4Moderate
Feb5Moderate
Mar5Moderate
Apr8Very high
May8Very high
Jun11Extreme
Jul10Extreme
Aug10Extreme
Sep8Very high
Oct6High
Nov4Moderate
Dec3Moderate
Location & terrain

Where is Imperial?

Imperial sits at 32.8°N, 115.6°W, -59 ft above sea level, in United States. The nearest listed city is El Centro, 3.7 mi away.

Topography around Imperial

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

Within 2 miles, the terrain around Imperial has only modest variations in elevation — a maximum elevation change of 33 ft around an average of -62 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 315 ft; within 50 miles, very significant variations in elevation — a maximum elevation change of 6,545 ft.

The land around Imperial is covered by cropland (47%), bare terrain (27%) and artificial surfaces (22%) within 2 miles, cropland (69%) and bare terrain (21%) within 10 miles, and bare terrain (61%) within 50 miles.

2 miles
33 ft
10 miles
315 ft
50 miles
6,545 ft
treesshrubsgrasslandcroplandartificial surfacesbare terrainwater
September weather nearby: El Centro 3.7 mi · Brawley 9.3 mi · Calexico 12 mi · Santa Isabel 15 mi · Mexicali 17 mi · Puebla 23 mi · Ciudad Guadalupe Victoria 47 mi · San Luis 52 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 Imperial (32.8475°, -115.5694°, elevation -59 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. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).