Colorado weather in September

In September, Colorado sees average daytime highs of 29°C and overnight lows near 18°C, with 91 mm of rain across 8 wet days and about 11.9 hours of daylight. It is the 8th-warmest and 7th-wettest month of the year here.

Day-to-day highs hold fairly steady near 29°C through the month. The sky is clear or mostly clear about 52% of the time in September, and the air most often feels comfortable.

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 Colorado's 4th-clearest and 1st-windiest month. For the whole year in context, see Colorado's year-round climate.

Daytime high
29°
8th warmest
Overnight low
18°
5th coldest
Rainfall
91 mm
8 wet days
Daylight
11 h 54 min
7:26 AM – 7:18 PM
Cloud cover
44%
4th clearest
Wind
11 km/h
1st windiest
Solar energy
5.36 kWh/m²
Travel score
5.9
out of 10

Colorado is human settlement in Brazil.

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 29°C through the month.

A typical September day in Colorado reaches about 29°C in the afternoon and slips back to 18°C overnight — a 11°C spread between the day's warmth and the night's chill. On most days the high lands between 23°C and 35°C. Set against its neighbours, September runs about 2°C warmer than August and about 1°C cooler than October.

10°20°30°40°151015202530
Avg high (°C)Avg low (°C)
12917
22917
32917
42917
52918
62918
72918
82918
92918
102918
112918
122918
132918
142918
152918
162918
172918
182918
192918
202918
212918
222918
232918
242918
252918
262918
272919
282919
292919
302919

How September really feels in Colorado

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.

Colorado weather by month

How September compares with the rest of the year at a glance. September is the 8th-warmest and 7th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan31° / 22°19519.113.23.5
Feb31° / 22°14716.912.83.6
Mar31° / 22°10513.212.24.4
Apr29° / 20°63711.55.9
May26° / 17°807.110.97.3
Jun25° / 15°616.110.67.8
Jul25° / 15°434.810.78.0
Aug28° / 16°444.311.27.5
Sep29° / 18°91811.95.9
Oct30° / 20°12711.812.54.7
Nov31° / 21°12412.313.14.3
Dec31° / 22°15216.713.43.8

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 52% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 11% of September, with mostly cloudy or overcast conditions the remaining 37%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
17723
27624
37525
47327
57228
67129
76931
86832
96733
106733
116535
126535
136436
146337
156337
166238
176238
186238
196139
206139
216040
225941
235842
245743
255644
265545
275446
285446
295347
305248

Chance of precipitation in September

Any precipitation

Colorado gets around 91 mm of rain over 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 26% and peaks near 35% on the wettest days. The odds climb toward the end of the month.

0%10%20%30%40%50%151015202530
Rain chance (%)
118
219
319
420
521
621
722
822
923
1023
1123
1223
1324
1424
1524
1625
1725
1826
1927
2027
2128
2229
2330
2431
2532
2633
2733
2834
2934
3035

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, September lands in the comfortable band about 31% 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 (%)
136382060
235382060
334382170
434382170
533382280
632372380
731362490
830362590
9303526100
10293427100
11283328100
12273229110
13263231120
14253131120
15243132130
16233033130
17233033140
18222933150
19212933160
20212933171
21202833181
22192832191
23182832211
24182831221
25172731232
26162730252
27162729262
28152629282
29142628293
30142528303

Wind in September

Winds average 11 km/h in September, the windiest month of the year.

Across September, daily wind ranges from about 11 km/h on the calmest days to 11 km/h at its breeziest. It stays fairly steady from day to day.

051015151015202530
Wind speed (km/h)Feels
111calm
211calm
311calm
411calm
511calm
611calm
711calm
811calm
911calm
1011calm
1111calm
1211calm
1311calm
1411calm
1511calm
1611calm
1711calm
1811calm
1911calm
2011calm
2111calm
2211calm
2311calm
2411calm
2511calm
2611calm
2711calm
2811calm
2911calm
3011calm

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 7:42 AM to 7:12 AM, and sunset from 7:14 PM to 7:23 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
111.57:427:14
211.67:417:14
311.67:407:14
411.67:397:15
511.67:387:15
611.67:377:15
711.77:357:16
811.77:347:16
911.77:337:16
1011.77:327:16
1111.87:317:17
1211.87:307:17
1311.87:297:17
1411.87:287:18
1511.87:277:18
1611.97:267:18
1711.97:257:19
1811.97:247:19
1911.97:237:19
2012.07:227:20
2112.07:217:20
2212.07:207:20
2312.07:197:20
2412.17:187:21
2512.17:177:21
2612.17:167:21
2712.17:157:22
2812.17:147:22
2912.27:137:22
3012.27:127:23

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 5.36 kWh/m².

For context, solar energy here swings from a low near 3.47 kWh/m² to a high of 6.23 kWh/m² in November across the year — September's 5.36 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
15.2Bright
25.2Bright
35.2Bright
45.2Bright
55.2Bright
65.2Bright
75.2Bright
85.3Bright
95.3Bright
105.3Bright
115.3Bright
125.3Bright
135.3Bright
145.3Bright
155.4Bright
165.4Bright
175.4Bright
185.4Bright
195.4Bright
205.5Bright
215.5Bright
225.5Bright
235.5Bright
245.5Bright
255.5Bright
265.5Bright
275.5Bright
285.5Bright
295.5Bright
305.6Bright
Planning a trip in September

Hazard calendar for Colorado

In seasonPeak

In September, Colorado sits inside its rainy season season. The full year is below, with each hazard's peak months called out.

Colorado's rainy season runs September–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 Colorado?

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

5.9
Sightseeing
5th-best month of the year
7.6
Beach & pool
2nd-best month of the year

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

What to pack for Colorado in September

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

In September, Colorado sees daytime highs around 29°C and nights near 18°C. Pack light clothes. Worth having: rain gear and sun protection. About 8 days see rain.

light clothesrain gearsun protection

UV index in Colorado in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 4 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Colorado peaks around January 20 at about 15 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near September 13 at about 5 (moderate).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecExtremeVery highHighExtremeJan 20UV 15Sep 13UV 5
UV index (midday)Level
Jan15Extreme
Feb15Extreme
Mar12Extreme
Apr9Very high
May7High
Jun6High
Jul5High
Aug7High
Sep4Moderate
Oct11Extreme
Nov13Extreme
Dec13Extreme

Air quality in Colorado 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 Colorado is worst in September — around 20 µg/m³ PM2.5 (moderate), about 2.9× the cleanest month (December, 7 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodSep 1620 µg/m³Dec 147 µg/m³
PM2.5 (µg/m³)Level
Jan8Good
Feb8Good
Mar8Good
Apr9Good
May10Good
Jun10Good
Jul10Good
Aug14Moderate
Sep20Moderate
Oct14Moderate
Nov7Good
Dec7Good
Location & terrain

Where is Colorado?

Colorado sits at 22.8°S, 52.0°W, 444 m above sea level, in Brazil. The nearest listed city is Teodoro Sampaio, 39 km away.

Topography around Colorado

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

Within 3 km, the terrain around Colorado has only modest variations in elevation — a maximum elevation change of 139 m around an average of 421 m above sea level; within 16 km, only modest variations in elevation — a maximum elevation change of 235 m; within 80 km, significant variations in elevation — a maximum elevation change of 551 m.

The land around Colorado is covered by grassland (38%) and cropland (38%) within 3 km, cropland (62%) and grassland (25%) within 16 km, and cropland (57%) and grassland (26%) within 80 km.

3 km
139 m
16 km
235 m
80 km
551 m
treesgrasslandcroplandartificial surfaceswater
September weather nearby: Teodoro Sampaio 39 km · Nova Esperança 45 km · Astorga 54 km · Jaguapitã 55 km · Paranavaí 57 km · Mandaguaçu 58 km · Mirante do Paranapanema 61 km · Maringá 65 km

Brazil travel facts

Travel advisory
Level 2
Exercise Increased Caution
Power plugs
Type C / N
127 / 220 V · 60 Hz
Prices
≈ 46% of US
price level, 2025
GDP per capita
$10,713
2025
Happiness
6.6 / 10
World Happiness, 2025
Safe drinking water
89%
of population, 2024
Homicide rate
19.3
per 100k, 2023
Road deaths
16
per 100k/yr, 2019
Income group
Upper middle
World Bank
English
Low
EF EPI 482
Religion
Roman Catholic 57%Evangelical 27%none 9%other 4%

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 Colorado (-22.8375°, -51.9731°, elevation 444 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).