Flower Mound weather in September

In September, Flower Mound sees average daytime highs of 87°F and overnight lows near 69°F, with 2.8 in of rain across 6.1 wet days and about 12.2 hours of daylight. It is the 4th-warmest and 8th-wettest month of the year here.

Highs ease over the month, from about 91°F in the first days to 84°F by the end. The sky is clear or mostly clear about 55% of the time in September, and the air most often feels muggy.

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 Flower Mound's 1st-clearest and 11th-windiest month. For the whole year in context, see Flower Mound's year-round climate.

Daytime high
87°
4th warmest
Overnight low
69°
9th coldest
Rainfall
2.8 in
6.1 wet days
Daylight
12 h 12 min
6:17 AM – 6:29 PM
Cloud cover
40%
1st clearest
Wind
7 mph
11th windiest
Solar energy
5.14 kWh/m²
Travel score
5.3
out of 10

Flower Mound is town in Denton County, Texas, United States.

Density
619/km²
people per km²

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

← AugustFlower Mound year-round climateOctober →Best places to visit in September
JanFebMarAprMayJunJulAugSepOctNovDec

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 91°F in the first days to 84°F by the end.

A typical September day in Flower Mound reaches about 87°F in the afternoon and slips back to 69°F overnight — a 18°F spread between the day's warmth and the night's chill. On most days the high lands between 78°F and 95°F. Set against its neighbours, September runs about 7°F cooler than August and about 10°F warmer than October.

60°80°100°151015202530
Avg high (°F)Avg low (°F)
19173
29173
39173
49173
59072
69072
79072
88971
98971
108971
118871
128870
138870
148770
158769
168769
178769
188668
198668
208667
218667
228567
238566
248566
258565
268465
278465
288464
298364
308364

How September really feels in Flower Mound

Once humidity and wind are folded in, September averages 12 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
12
heat index over the day's high
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.

Flower Mound weather by month

How September compares with the rest of the year at a glance. September is the 4th-warmest and 8th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan56° / 38°2.76.90.510.14.1
Feb60° / 41°2.77.10.610.85.2
Mar67° / 49°3.78.90.211.76.5
Apr75° / 56°4.18.2012.87.2
May82° / 65°5.210.9013.76.0
Jun90° / 73°3.27.7014.14.3
Jul94° / 76°1.85.40143.2
Aug94° / 76°2.05.2013.23.3
Sep87° / 69°2.86.1012.25.3
Oct77° / 58°3.87.5011.27.4
Nov66° / 47°3.56.80.110.36.7
Dec57° / 40°3.46.90.39.94.5

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 55% of the time in September, the clearest month of the year.

Beyond those clear spells, partly cloudy skies cover about 16% of September, with mostly cloudy or overcast conditions the remaining 29%. Skies tend to open up as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
17327
27228
37228
47129
57030
66931
76931
86931
96832
106832
116832
126832
136832
146832
156832
166832
176832
186931
197030
207129
217228
227327
237426
247525
257525
267624
277624
287624
297624
307624

Chance of precipitation in September

Any precipitation

Flower Mound gets around 2.8 in of rain over 6.1 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 21% and peaks near 24% on the wettest days.

0%10%20%30%151015202530
Rain chance (%)
121
221
321
422
522
623
723
823
923
1024
1124
1224
1324
1424
1524
1623
1723
1822
1922
2021
2120
2219
2318
2417
2517
2616
2716
2816
2917
3017

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, September lands in the muggy band about 31% of days. Sticky, muggy-or-worse air turns up on roughly 52% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
137223928
247233828
348233728
458233727
568233627
668233626
779223626
889223626
989213526
1099203526
111010203525
121010193525
131111193525
141112183424
151212183423
161213183423
171313183322
181414183321
191515183220
201716183119
211817183018
222018182816
232118182715
242319192614
252519192413
262619192312
272819202211
283019202110
293119202010
30331920199

Wind in September

Winds average 7 mph in September.

Across September, daily wind ranges from about 7 mph on the calmest days to 7 mph at its breeziest. It stays fairly steady from day to day.

0246810151015202530
Wind speed (mph)Feels
17calm
27calm
37calm
47calm
57calm
67calm
77calm
87calm
97calm
107calm
117calm
127calm
137calm
147calm
157calm
167calm
177calm
187calm
197calm
207calm
217calm
227calm
237calm
247calm
257calm
267calm
277calm
287calm
297light breeze
307light breeze

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 6:07 AM to 6:26 AM, and sunset from 6:50 PM to 6:09 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.76:076:50
212.76:076:48
312.66:086:47
412.66:096:46
512.66:096:44
612.56:106:43
712.56:116:41
812.56:116:40
912.46:126:39
1012.46:136:37
1112.46:136:36
1212.36:146:34
1312.36:156:33
1412.36:156:32
1512.26:166:30
1612.26:176:29
1712.26:176:27
1812.16:186:26
1912.16:196:24
2012.16:196:23
2112.06:206:22
2212.06:216:20
2312.06:216:19
2411.96:226:17
2511.96:236:16
2611.96:246:15
2711.86:246:13
2811.86:256:12
2911.76:266:10
3011.76:266:09

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 5.14 kWh/m².

For context, solar energy here swings from a low near 2.58 kWh/m² to a high of 6.8 kWh/m² in July across the year — September's 5.14 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
15.7Bright
25.6Bright
35.6Bright
45.5Bright
55.5Bright
65.4Bright
75.4Bright
85.3Bright
95.3Bright
105.3Bright
115.2Bright
125.2Bright
135.1Bright
145.1Bright
155.1Bright
165.1Bright
175.0Bright
185.0Bright
195.0Bright
205.0Bright
215.0Bright
225.0Bright
235.0Bright
244.9Bright
254.9Bright
264.9Bright
274.9Bright
284.8Bright
294.8Bright
304.8Bright
Planning a trip in September

Hazard calendar for Flower Mound

In seasonPeak

In September, Flower Mound sits inside its atlantic hurricane season. The full year is below, with each hazard's peak months called out.

Flower Mound sits in the Atlantic hurricane belt; the season peaks August–October.

Atlantic hurricane
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec

Is September a good time to visit Flower Mound?

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

5.3
Sightseeing
6th-best month of the year
7.5
Beach & pool
1st-best month of the year

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

What to pack for Flower Mound in September

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

In September, Flower Mound sees daytime highs around 87°F and nights near 69°F. Pack light clothes. Worth having: sun protection. About 6 days see rain.

light clothessun protection

UV index in Flower Mound in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 7 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Flower Mound peaks around July 14 at about 10 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 21 at about 3 (moderate).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highExtremeVery highHighModerateJul 14UV 10Dec 21UV 3
UV index (midday)Level
Jan3Moderate
Feb5Moderate
Mar6High
Apr9Very high
May9Very high
Jun10Extreme
Jul10Extreme
Aug10Very high
Sep7Very high
Oct6High
Nov4Moderate
Dec3Moderate

Air quality in Flower Mound 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 Flower Mound is worst in July — around 19 µg/m³ PM2.5 (moderate), about 2.6× the cleanest month (October, 8 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodJul 1519 µg/m³Oct 248 µg/m³
PM2.5 (µg/m³)Level
Jan8Good
Feb8Good
Mar10Good
Apr11Good
May14Moderate
Jun16Moderate
Jul19Moderate
Aug15Moderate
Sep11Good
Oct8Good
Nov8Good
Dec8Good
Location & terrain

Where is Flower Mound?

Flower Mound sits at 33.0°N, 97.1°W, 604 ft above sea level, in United States. The nearest listed city is Southlake, 5.6 mi away.

Topography around Flower Mound

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

Within 2 miles, the terrain around Flower Mound has only modest variations in elevation — a maximum elevation change of 157 ft around an average of 597 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 387 ft; within 50 miles, significant variations in elevation — a maximum elevation change of 1,043 ft.

The land around Flower Mound is covered by trees (37%), artificial surfaces (25%) and water (21%) within 2 miles, trees (32%), artificial surfaces (31%) and grassland (25%) within 10 miles, and grassland (49%) and trees (25%) within 50 miles.

2 miles
157 ft
10 miles
387 ft
50 miles
1,043 ft
treesgrasslandcroplandartificial surfacesbare terrainwater
← AugustFlower Mound year-round climateOctober →Best places to visit in September
September weather nearby: Southlake 5.6 mi · Grapevine 5.6 mi · Highland Village 6.2 mi · Coppell 6.2 mi · Lewisville 6.2 mi · Corinth 9.9 mi · Colleyville 9.9 mi · Keller 11 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 Flower Mound (33.0146°, -97.097°, elevation 604 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. Tropical-cyclone seasons are the published climatological basin seasons (NOAA National Hurricane Center / regional warning centres). 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).