San Bernardino weather in September

In September, San Bernardino sees average daytime highs of 27°C and overnight lows near 16°C, with 113 mm of rain across 8.6 wet days and about 11.8 hours of daylight. It is the 8th-warmest and 8th-wettest month of the year here.

Day-to-day highs hold fairly steady near 27°C through the month. The sky is clear or mostly clear about 53% of the time in September, and the air most often feels dry.

Daylight stretches from about 11 h 30 min at the start of September to 12 h 12 min by month's end. Set against the rest of the year, September is San Bernardino's 2nd-clearest and 2nd-windiest month. For the whole year in context, see San Bernardino's year-round climate.

Daytime high
27°
8th warmest
Overnight low
16°
5th coldest
Rainfall
113 mm
8.6 wet days
Daylight
11 h 54 min
6:48 AM – 6:39 PM
Cloud cover
43%
2nd clearest
Wind
14 km/h
2nd windiest
Solar energy
4.89 kWh/m²
Travel score
6.9
out of 10

San Bernardino is district of Paraguay.

Density
41/km²
people per km²
Founded
1881

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 27°C through the month.

A typical September day in San Bernardino reaches about 27°C in the afternoon and slips back to 16°C overnight — a 11°C spread between the day's warmth and the night's chill. On most days the high lands between 19°C and 35°C. Set against its neighbours, September runs about 2°C warmer than August and about 2°C cooler than October.

10°20°30°40°151015202530
Avg high (°C)Avg low (°C)
12716
22716
32716
42716
52716
62716
72716
82716
92716
102716
112716
122716
132716
142716
152716
162716
172716
182716
192717
202717
212717
222717
232817
242817
252817
262817
272817
282818
292818
302818

How September really feels in San Bernardino

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

Days feeling ≥ 32°C
0
heat index over the day's high
Days feeling ≤ C
0
wind chill below the day's low

September sits comfortably in between — no days that feel dangerously hot or drop to a hard freeze once humidity and wind are folded in.

San Bernardino weather by month

How September compares with the rest of the year at a glance. September is the 8th-warmest and 8th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan33° / 23°12412.913.43.5
Feb32° / 23°14212.312.93.7
Mar31° / 22°10910.312.24.6
Apr28° / 19°1428.911.46.2
May24° / 16°1308.810.87.2
Jun23° / 14°978.310.57.1
Jul23° / 13°827.710.67.4
Aug26° / 15°706.611.17.7
Sep27° / 16°1138.611.86.9
Oct29° / 19°19612.112.65.3
Nov30° / 20°17711.113.24.8
Dec32° / 22°16312.713.53.9

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 53% 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 38%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
17129
27030
37030
46931
56832
66733
76634
86634
96535
106436
116436
126436
136337
146337
156337
166337
176238
186238
196238
206040
216040
226040
235842
245842
255842
265644
275644
285545
295545
305545

Chance of precipitation in September

Any precipitation

San Bernardino gets around 113 mm of rain over 8.6 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 28% and peaks near 36% on the wettest days. The odds climb toward the end of the month.

0%10%20%30%40%50%151015202530
Rain chance (%)
122
222
322
423
523
623
724
824
925
1025
1125
1226
1326
1427
1527
1628
1728
1829
1930
2031
2132
2232
2333
2434
2534
2635
2735
2835
2935
3036

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 33% of days. Sticky, muggy-or-worse air turns up on roughly 19% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
140292280
239302280
339302390
438292390
5382923100
6382923100
7382823100
8372824111
9372724111
10372724121
11362624121
12362625131
13362525141
14352425141
15352425151
16342425161
17342325171
18342325181
19332324191
20322324202
21312324212
22302324222
23292324232
24272324243
25262324253
26242324263
27232224273
28222224284
29212224294
30192224304

Wind in September

Winds average 14 km/h in September.

Across September, daily wind ranges from about 14 km/h on the calmest days to 14 km/h at its breeziest. It stays fairly steady from day to day.

05101520151015202530
Wind speed (km/h)Feels
114light breeze
214light breeze
314light breeze
414light breeze
514light breeze
614light breeze
714light breeze
814light breeze
914light breeze
1014light breeze
1114light breeze
1214light breeze
1314light breeze
1414light breeze
1514light breeze
1614light breeze
1714light breeze
1814light breeze
1914light breeze
2014light breeze
2114light breeze
2214light breeze
2314light breeze
2414light breeze
2514light breeze
2614light breeze
2714light breeze
2814light breeze
2914light breeze
3014light breeze

Sunrise & sunset in September

DaylightNight

Daylight runs from about 11 h 30 min at the start of September to 12 h 12 min by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 42 minutes over September. Sunrise moves from 7:05 AM to 6:32 AM, and sunset from 6:33 PM to 6:45 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
111.57:056:33
211.57:036:34
311.57:026:34
411.67:016:34
511.67:006:35
611.66:596:35
711.66:586:36
811.76:576:36
911.76:566:36
1011.76:556:37
1111.76:546:37
1211.86:526:38
1311.86:516:38
1411.86:506:38
1511.86:496:39
1611.96:486:39
1711.96:476:40
1811.96:466:40
1911.96:446:40
2012.06:436:41
2112.06:426:41
2212.06:416:41
2312.06:406:42
2412.16:396:42
2512.16:386:43
2612.16:376:43
2712.16:366:44
2812.26:346:44
2912.26:336:44
3012.26:326:45

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.89 kWh/m².

For context, solar energy here swings from a low near 2.8 kWh/m² to a high of 6.7 kWh/m² in December across the year — September's 4.89 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
14.6Bright
24.7Bright
34.7Bright
44.7Bright
54.7Bright
64.8Bright
74.8Bright
84.8Bright
94.8Bright
104.8Bright
114.8Bright
124.8Bright
134.9Bright
144.9Bright
154.9Bright
164.9Bright
174.9Bright
185.0Bright
195.0Bright
205.0Bright
215.0Bright
225.0Bright
235.0Bright
245.0Bright
255.0Bright
265.0Bright
275.1Bright
285.1Bright
295.1Bright
305.1Bright
Planning a trip in September

Is September a good time to visit San Bernardino?

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

6.9
Sightseeing
5th-best month of the year
7.1
Beach & pool
2nd-best month of the year

September is a reasonable time to visit San Bernardino for sightseeing. The water and warmth also suit a beach or pool day.

What to pack for San Bernardino in September

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

In September, San Bernardino sees daytime highs around 27°C and nights near 16°C. Pack light clothes. Worth having: rain gear and sun protection. About 9 days see rain.

light clothesrain gearsun protection

UV index in San Bernardino 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 San Bernardino peaks around January 17 at about 15 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near July 15 at about 5 (moderate).

The index reaches 3 or more — the level where the WHO recommends sun protection — every month of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecExtremeVery highHighModerateHighVery highExtremeJan 17UV 15Jul 15UV 5
UV index (midday)Level
Jan15Extreme
Feb14Extreme
Mar11Extreme
Apr9Very high
May6High
Jun5Moderate
Jul5Moderate
Aug5High
Sep8Very high
Oct8Very high
Nov12Extreme
Dec13Extreme

Air quality in San Bernardino 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 San Bernardino is worst in September — around 28 µg/m³ PM2.5 (moderate), about 2.9× the cleanest month (December, 10 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodGoodModerateGoodSep 1227 µg/m³Dec 1910 µg/m³
PM2.5 (µg/m³)Level
Jan11Good
Feb12Moderate
Mar11Good
Apr13Moderate
May13Moderate
Jun15Moderate
Jul17Moderate
Aug25Moderate
Sep28Moderate
Oct18Moderate
Nov13Moderate
Dec10Good
Location & terrain

Where is San Bernardino?

San Bernardino sits at 25.3°S, 57.3°W, 0 m above sea level, in Paraguay. The nearest listed city is Areguá, 9.0 km away.

Topography around San Bernardino

How much the land rises and falls, and what covers it, within 3, 16 and 80 km of San Bernardino.

Within 3 km, the terrain around San Bernardino has only modest variations in elevation — a maximum elevation change of 183 m around an average of 91 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 272 m; within 80 km, significant variations in elevation — a maximum elevation change of 529 m.

The land around San Bernardino is covered by trees (51%) and water (42%) within 3 km, trees (72%) within 16 km, and grassland (52%) and trees (39%) within 80 km.

3 km
183 m
16 km
272 m
80 km
529 m
treesgrasslandcroplandartificial surfaceswaterwetland
September weather nearby: Areguá 9.0 km · Itauguá 11 km · Capiatá 16 km · Caacupé 18 km · San Lorenzo 22 km · Itá 22 km · Fernando de la Mora 23 km · Limpio 25 km

Paraguay travel facts

Travel advisory
Level 1
Exercise Normal Precautions
Power plugs
Type A / B / C / N
220 V · 50 Hz
Prices
≈ 35% of US
price level, 2025
GDP per capita
$7,027
2025
Happiness
6.2 / 10
World Happiness, 2025
Safe drinking water
64%
of population, 2024
Homicide rate
6.8
per 100k, 2023
Road deaths
22
per 100k/yr, 2019
Income group
Upper middle
World Bank
English
Moderate
EF EPI 531
Religion
Roman Catholic 80%Protestant 7%Believer 6%other 1%

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 San Bernardino (-25.3107°, -57.2963°, elevation 0 m), 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. 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).