Altamonte Springs weather in September

In September, Altamonte Springs sees average daytime highs of 87°F and overnight lows near 74°F, with 5.2 in of rain across 18.4 wet days and about 12.2 hours of daylight. It is the 4th-warmest and 4th-wettest month of the year here.

Day-to-day highs hold fairly steady near 87°F through the month. The sky is clear or mostly clear about 22% of the time in September, and the air most often feels oppressive.

Daylight stretches from about 12 h 36 min at the start of September to 11 h 48 min by month's end. Set against the rest of the year, September is Altamonte Springs's 9th-clearest and 9th-windiest month. For the whole year in context, see Altamonte Springs's year-round climate.

Daytime high
87°
4th warmest
Overnight low
74°
10th coldest
Rainfall
5.2 in
18.4 wet days
Daylight
12 h 12 min
6:15 AM – 6:25 PM
Cloud cover
67%
9th clearest
Wind
5 mph
9th windiest
Solar energy
4.61 kWh/m²
Travel score
3.7
out of 10

Altamonte Springs is city in Seminole County, Florida, United States.

Density
1,723/km²
people per km²
Founded
1920

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 87°F through the month.

A typical September day in Altamonte Springs reaches about 87°F in the afternoon and slips back to 74°F overnight — a 13°F spread between the day's warmth and the night's chill. On most days the high lands between 83°F and 90°F. Set against its neighbours, September runs about 2°F cooler than August and about 5°F warmer than October.

60°70°80°90°151015202530
Avg high (°F)Avg low (°F)
18875
28875
38875
48875
58874
68874
78874
88874
98874
108774
118774
128774
138774
148774
158774
168774
178774
188773
198773
208773
218673
228673
238673
248673
258673
268672
278672
288572
298572
308572

How September really feels in Altamonte Springs

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
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.

Altamonte Springs 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
Jan69° / 50°2.16.410.47.1
Feb72° / 53°2.06.6117.2
Mar76° / 57°2.36.311.87.6
Apr81° / 62°2.17.112.76.9
May86° / 68°2.89.413.45.2
Jun89° / 73°5.819.913.83.3
Jul89° / 75°5.921.913.62.9
Aug89° / 75°6.522.9132.8
Sep87° / 74°5.218.412.23.7
Oct82° / 67°2.710.511.36.1
Nov76° / 59°1.35.410.67.7
Dec71° / 53°2.05.310.27.4

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 22% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 18% of September, with mostly cloudy or overcast conditions the remaining 60%. Skies tend to open up as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
13268
23268
33367
43367
53466
63466
73565
83565
93664
103763
113862
123961
133961
144060
154159
164159
174258
184258
194258
204258
214357
224357
234456
244456
254456
264456
274456
284555
294555
304654

Chance of precipitation in September

Any precipitation

Altamonte Springs gets around 5.2 in of rain over 18.4 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 61% and peaks near 70% on the wettest days. The odds ease toward the end of the month.

0%20%40%60%80%151015202530
Rain chance (%)
170
269
369
468
568
667
767
866
965
1065
1164
1263
1363
1462
1562
1661
1760
1860
1959
2059
2158
2257
2357
2456
2556
2655
2754
2853
2953
3052

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, September lands in the oppressive band about 68% of days. Sticky, muggy-or-worse air turns up on roughly 97% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)Miserable (%)
100076726
200086725
300086923
400096922
500097021
6000107020
7000107119
8001117018
9001117117
10001127116
11001127215
12001137115
13001137214
14001147114
15001147213
16002157013
17002157013
18002167012
19003166912
20003166912
21013176811
22014176711
23014176810
24024176710
25025186510
2612518659
2713618639
2813619629
2913719628
3014719618

Wind in September

Winds average 5 mph in September.

Across September, daily wind ranges from about 5 mph on the calmest days to 6 mph at its breeziest. It stays fairly steady from day to day.

0246810151015202530
Wind speed (mph)Feels
15calm
25calm
35calm
45calm
55calm
65calm
75calm
85calm
95calm
105calm
115calm
125calm
135calm
145calm
155calm
165calm
175calm
185calm
196calm
206calm
216calm
226calm
236calm
246calm
256calm
266calm
276calm
286calm
296calm
306calm

Sunrise & sunset in September

DaylightNight

Daylight runs from about 12 h 36 min at the start of September to 11 h 48 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 48 minutes over September. Sunrise moves from 6:07 AM to 6:22 AM, and sunset from 6:43 PM to 6:08 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.66:076:43
212.66:086:42
312.56:086:41
412.56:096:40
512.56:096:38
612.56:106:37
712.46:106:36
812.46:116:35
912.46:116:34
1012.36:126:32
1112.36:126:31
1212.36:136:30
1312.36:136:29
1412.26:146:27
1512.26:146:26
1612.26:156:25
1712.16:156:24
1812.16:166:22
1912.16:166:21
2012.16:176:20
2112.06:176:19
2212.06:186:17
2312.06:186:16
2411.96:196:15
2511.96:196:14
2611.96:206:12
2711.86:206:11
2811.86:216:10
2911.86:216:09
3011.86:226:08

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.61 kWh/m².

For context, solar energy here swings from a low near 2.92 kWh/m² to a high of 6.19 kWh/m² in May across the year — September's 4.61 kWh/m² falls in the middle.

024151015202530
Solar energy (kWh/m²)Level
15.0Bright
25.0Bright
34.9Bright
44.9Bright
54.9Bright
64.8Bright
74.8Bright
84.8Bright
94.8Bright
104.7Bright
114.7Bright
124.7Bright
134.7Bright
144.7Bright
154.6Bright
164.6Bright
174.6Bright
184.6Bright
194.5Bright
204.5Bright
214.5Bright
224.5Bright
234.4Bright
244.4Bright
254.4Bright
264.3Bright
274.3Bright
284.3Bright
294.3Bright
304.2Bright
Planning a trip in September

Hazard calendar for Altamonte Springs

In seasonPeak

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

Altamonte Springs sits in the Atlantic hurricane belt; the season peaks August–October.

Altamonte Springs's rainy season runs June–September, when most of the year's rain falls.

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

Is September a good time to visit Altamonte Springs?

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

3.7
Sightseeing
9th-best month of the year
5.3
Beach & pool
6th-best month of the year

September is a weaker month for outdoor sightseeing in Altamonte Springs.

What to pack for Altamonte Springs in September

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

In September, Altamonte Springs sees daytime highs around 87°F and nights near 74°F. Pack light clothes and rain gear. Worth having: sun protection. About 18 days see rain.

light clothesrain gearsun protection

Sea temperature near Altamonte Springs in September

The nearest coast averages about 82°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 44 mi away) is warmest in September at about 82°F and coldest in February near 67°F.

It's comfortable for a long swim from Mar 15 to Jan 17 — about 10.2 months when the water holds above 68°F.

65°70°75°80°85°JanFebMarAprMayJunJulAugSepOctNovDeccoolrefreshingwarmtropicalcomfortable to swim
Sea temperature (°F)Comfort
Jan68Refreshing
Feb67Cool
Mar68Refreshing
Apr71Refreshing
May76Warm
Jun80Warm
Jul82Warm
Aug82Warm
Sep82Warm
Oct79Warm
Nov74Refreshing
Dec70Refreshing

UV index in Altamonte Springs in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 9 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Altamonte Springs peaks around July 15 at about 11 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 20 at about 4 (moderate).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highExtremeVery highHighModerateJul 15UV 11Dec 20UV 4
UV index (midday)Level
Jan4Moderate
Feb6High
Mar8Very high
Apr8Very high
May9Very high
Jun10Extreme
Jul11Extreme
Aug10Very high
Sep9Very high
Oct7High
Nov5High
Dec4Moderate

Air quality in Altamonte Springs 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 Altamonte Springs is worst in July — around 19 µg/m³ PM2.5 (moderate), about 2.7× the cleanest month (December, 7 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodJul 1019 µg/m³Dec 137 µg/m³
PM2.5 (µg/m³)Level
Jan9Good
Feb11Good
Mar15Moderate
Apr13Moderate
May13Moderate
Jun19Moderate
Jul19Moderate
Aug16Moderate
Sep11Good
Oct9Good
Nov8Good
Dec7Good
Location & terrain

Where is Altamonte Springs?

Altamonte Springs sits at 28.7°N, 81.4°W, 85 ft above sea level, in United States. The nearest listed city is Maitland, 2.5 mi away.

Topography around Altamonte Springs

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

Within 2 miles, the terrain around Altamonte Springs has only modest variations in elevation — a maximum elevation change of 112 ft around an average of 92 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 190 ft; within 50 miles, only modest variations in elevation — a maximum elevation change of 322 ft.

The land around Altamonte Springs is covered by trees (51%) and artificial surfaces (35%) within 2 miles, trees (58%) and artificial surfaces (26%) within 10 miles, and trees (57%) within 50 miles.

2 miles
112 ft
10 miles
190 ft
50 miles
322 ft
treesgrasslandartificial surfacesbare terrainwaterwetland
September weather nearby: Maitland 2.5 mi · Casselberry 2.5 mi · Winter Springs 4.3 mi · Wekiwa Springs 4.3 mi · Winter Park 4.3 mi · Lake Mary 7.5 mi · Orlando 8.7 mi · Pine Hills 8.7 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 Altamonte Springs (28.6611°, -81.3656°, elevation 85 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). 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).