Slidell weather in September

In September, Slidell sees average daytime highs of 83°F and overnight lows near 74°F, with 4.7 in of rain across 12.5 wet days and about 12.2 hours of daylight. It is the 4th-warmest and 5th-wettest month of the year here.

Highs ease over the month, from about 85°F in the first days to 81°F by the end. The sky is clear or mostly clear about 46% 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 42 min by month's end. Set against the rest of the year, September is Slidell's 4th-clearest and 9th-windiest month. For the whole year in context, see Slidell's year-round climate.

Daytime high
83°
4th warmest
Overnight low
74°
9th coldest
Rainfall
4.7 in
12.5 wet days
Daylight
12 h 12 min
5:48 AM – 5:59 PM
Cloud cover
49%
4th clearest
Wind
7 mph
9th windiest
Solar energy
4.94 kWh/m²
Travel score
5.5
out of 10

Slidell is city in St. Tammany Parish, Louisiana, United States.

Density
32,119/km²
people per km²
Founded
1882

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 85°F in the first days to 81°F by the end.

A typical September day in Slidell reaches about 83°F in the afternoon and slips back to 74°F overnight — a 10°F spread between the day's warmth and the night's chill. On most days the high lands between 79°F and 87°F. Set against its neighbours, September runs about 3°F cooler than August and about 7°F warmer than October.

60°70°80°90°151015202530
Avg high (°F)Avg low (°F)
18576
28576
38576
48576
58576
68576
78576
88576
98576
108575
118475
128475
138475
148475
158474
168474
178374
188374
198374
208373
218373
228373
238273
248272
258272
268271
278171
288171
298171
308170

How September really feels in Slidell

Once humidity and wind are folded in, September averages 15 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
15
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.

Slidell weather by month

How September compares with the rest of the year at a glance. September is the 4th-warmest and 5th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysDaylight (hours)Travel score
Jan59° / 47°4.59.310.34.6
Feb62° / 51°4.48.710.95.4
Mar67° / 56°4.89.211.86.5
Apr73° / 63°3.88.712.77.1
May80° / 71°3.59.913.56.8
Jun85° / 76°4.91513.94.7
Jul87° / 78°5.118.113.84.0
Aug87° / 78°5.917.913.14.0
Sep83° / 74°4.712.512.25.5
Oct76° / 65°3.47.611.37.5
Nov67° / 55°3.3710.56.9
Dec61° / 50°4.09.110.15.2

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 46% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 15% of September, with mostly cloudy or overcast conditions the remaining 39%. Skies tend to open up as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
15248
25347
35446
45446
55545
65644
75743
85743
95842
105941
116040
126040
136040
146238
156238
166238
176139
186238
196337
206337
216337
226436
236436
246535
256535
266634
276733
286733
296733
306832

Chance of precipitation in September

Any precipitation

Slidell gets around 4.7 in of rain over 12.5 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 42% and peaks near 52% on the wettest days. The odds ease toward the end of the month.

0%20%40%60%151015202530
Rain chance (%)
152
251
350
450
549
648
748
847
946
1045
1144
1244
1343
1443
1543
1642
1742
1841
1941
2040
2139
2238
2337
2436
2535
2634
2733
2832
2931
3030

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 47% of days. Sticky, muggy-or-worse air turns up on roughly 88% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)Miserable (%)
101174645
201174743
301284841
401284939
502285038
602295136
702295235
802295334
9023105233
10023105431
11033115330
12034115230
13034125229
14034135228
15134135128
16135145027
17145155026
18145164925
19155164824
20256174723
21266184622
22376184521
23377194419
24487204318
25588204217
26599204115
27699214014
2871010213913
2971011213812
3081111213711

Wind in September

Winds average 7 mph in September.

Across September, daily wind ranges from about 7 mph on the calmest days to 8 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
257light breeze
268light breeze
278light breeze
288light breeze
298light breeze
308light breeze

Sunrise & sunset in September

DaylightNight

Daylight runs from about 12 h 36 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 54 minutes over September. Sunrise moves from 5:40 AM to 5:56 AM, and sunset from 6:18 PM to 5:41 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.65:406:18
212.65:406:17
312.65:416:16
412.65:416:14
512.55:426:13
612.55:426:12
712.55:436:11
812.45:446:09
912.45:446:08
1012.45:456:07
1112.35:456:05
1212.35:466:04
1312.35:466:03
1412.25:476:01
1512.25:476:00
1612.25:485:59
1712.15:495:58
1812.15:495:56
1912.15:505:55
2012.15:505:54
2112.05:515:52
2212.05:515:51
2312.05:525:50
2411.95:535:48
2511.95:535:47
2611.95:545:46
2711.85:545:45
2811.85:555:43
2911.85:565:42
3011.75:565:41

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.94 kWh/m².

For context, solar energy here swings from a low near 2.72 kWh/m² to a high of 6.27 kWh/m² in May across the year — September's 4.94 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
15.2Bright
25.2Bright
35.1Bright
45.1Bright
55.1Bright
65.1Bright
75.1Bright
85.1Bright
95.1Bright
105.0Bright
115.0Bright
125.0Bright
135.0Bright
145.0Bright
155.0Bright
164.9Bright
174.9Bright
184.9Bright
194.9Bright
204.8Bright
214.8Bright
224.8Bright
234.8Bright
244.8Bright
254.8Bright
264.8Bright
274.7Bright
284.7Bright
294.7Bright
304.7Bright
Planning a trip in September

Hazard calendar for Slidell

In seasonPeak

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

Slidell 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 Slidell?

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

5.5
Sightseeing
6th-best month of the year
6.6
Beach & pool
2nd-best month of the year

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

What to pack for Slidell in September

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

In September, Slidell sees daytime highs around 83°F and nights near 74°F. Pack light clothes. Worth having: rain gear and sun protection. About 13 days see rain.

light clothesrain gearsun protection

Sea temperature near Slidell in September

The nearest coast averages about 83°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 12 mi away) is warmest in August at about 86°F and coldest in January near 57°F.

It's comfortable for a long swim from Apr 5 to Nov 10 — about 7.2 months when the water holds above 68°F.

50°60°70°80°90°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmtropicalcomfortable to swim
Sea temperature (°F)Comfort
Jan57Bracing
Feb58Bracing
Mar64Cool
Apr71Refreshing
May78Warm
Jun84Tropical
Jul86Tropical
Aug86Tropical
Sep83Tropical
Oct75Warm
Nov67Cool
Dec60Cool

UV index in Slidell 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 Slidell peaks around July 12 at about 10 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 19 at about 4 (moderate).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highVery highHighModerateJul 12UV 10Dec 19UV 4
UV index (midday)Level
Jan4Moderate
Feb6High
Mar6High
Apr10Very high
May10Very high
Jun10Very high
Jul10Extreme
Aug9Very high
Sep8Very high
Oct6High
Nov5Moderate
Dec4Moderate

Air quality in Slidell 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 Slidell is worst in July — around 22 µg/m³ PM2.5 (moderate), about 2.9× the cleanest month (November, 8 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodJul 1621 µg/m³Nov 238 µg/m³
PM2.5 (µg/m³)Level
Jan8Good
Feb9Good
Mar10Good
Apr10Good
May13Moderate
Jun18Moderate
Jul22Moderate
Aug17Moderate
Sep11Good
Oct8Good
Nov8Good
Dec8Good
Location & terrain

Where is Slidell?

Slidell sits at 30.3°N, 89.8°W, 3 ft above sea level, in United States. The nearest listed city is Chalmette, 25 mi away.

Topography around Slidell

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

Within 2 miles, the terrain around Slidell has only modest variations in elevation — a maximum elevation change of 62 ft around an average of 16 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 118 ft; within 50 miles, only modest variations in elevation — a maximum elevation change of 423 ft.

The land around Slidell is covered by trees (56%) and artificial surfaces (25%) within 2 miles, trees (52%) and water (26%) within 10 miles, and trees (44%) and water (34%) within 50 miles.

2 miles
62 ft
10 miles
118 ft
50 miles
423 ft
treesgrasslandartificial surfacesbare terrainwaterwetland
September weather nearby: Chalmette 25 mi · New Orleans 28 mi · Terrytown 29 mi · Gretna 30 mi · Metairie 30 mi · Metairie Terrace 30 mi · Harvey 31 mi · Marrero 32 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 Slidell (30.2752°, -89.7812°, elevation 3 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).