Slidell climate — normals and trends
Slidell (United States) has a humid subtropical climate (Cfa) under the Köppen-Geiger classification. Its mean annual temperature is 20.2 °C and it receives 1,266 mm of precipitation per year.
These figures are normals computed over 86 complete calendar years, from 1940 to 2025, using ERA5 reanalysis data from the Copernicus programme.
The warmest month is July (27.7 °C on average) and the coldest is January (11.3 °C). Rainfall peaks in August.
Slidell averages 3 frost days, 53 hot days (≥ 30 °C) and 134 rainy days per year.
Slidell has warmed by +1.0 °C between 1940 and 2025, or +0.12 °C per decade. This trend is statistically significant.
The hottest day of the period reached 36.8 °C (on 26 August 1943) and the coldest -10.8 °C (on 21 January 1985).
Data from ERA5 reanalysis (Copernicus Climate Change Service), redistributed under a CC-BY 4.0 licence. Normals are recomputed whenever the archive is updated.
Climate normals · ERA5
SlidellLouisiana
- coords
- 30.28°, -89.78°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
20.2°C
Average daily high
23.1°C
Average daily low
17.4°C
Annual rainfall
1,266mm
Sunshine / day
9.8h
Mean relative humidity
78%
Average peak wind
18.2km/h
Seasonal range
16.4°C
Frost days (< 0 °C)
3 d/yr
Hot days (≥ 30 °C)
53 d/yr
Rainy days (≥ 1 mm)
134 d/yr
Annual snowfall
0.5 cm
Average feels-like high
24.9 °C
Average feels-like low
17.6 °C
Average peak gust
33.8 km/h
Tropical nights (≥ 20 °C)
164 d/yr
Solar radiation
16.9 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+1.0 °C
since 1940
+0.1 °C per decade · r² = 0.23 · p = < 0.001
Trend fitted by linear regression (ordinary least squares) on annual means. A trend is shown only when it is statistically significant (p < 0.05).
A climograph overlays rainfall (bars) and temperature (line): the standard reading in climatology, where you can see at a glance whether the warm season is also the dry one.
Records for the period
Hottest day
36.8 °C
26 August 1943
Coldest day
-10.8 °C
21 January 1985
Wettest day
291 mm
29 August 2012
Windiest day
104.5 km/h
29 August 2005
Strongest gust
193.7 km/h
29 August 2005
Hottest feels-like
43.4 °C
2 August 2010
Coldest feels-like
-18.7 °C
23 December 1989
Snowiest day
8.5 cm
21 January 2025
Sunniest day
14.0 h
19 June 1940
Normals computed over complete calendar years 1940–2025.
A specific year
Pick a year and see how it compares to normal — warmer, drier or more extreme than usual?
Across the whole year
Month by month
| High | vs. normal | Precipitation | vs. normal | |
|---|---|---|---|---|
| Jan | 13.1 °C | -1.4 °C | 80 mm | -26 mm |
| Feb | 18.4 °C | +2.2 °C | 142 mm | +28 mm |
| Mar | 21.3 °C | +1.9 °C | 111 mm | -18 mm |
| Apr | 24.6 °C | +1.7 °C | 74 mm | -22 mm |
| May | 27.2 °C | +0.6 °C | 191 mm | +105 mm |
| Jun | 30.0 °C | +0.7 °C | 85 mm | -14 mm |
| Jul | 31.2 °C | +1.1 °C | 115 mm | -12 mm |
| Aug | 30.7 °C | +0.5 °C | 110 mm | -19 mm |
| Sep | 29.6 °C | +1.2 °C | 23 mm | -99 mm |
| Oct | 25.8 °C | +1.4 °C | 126 mm | +58 mm |
| Nov | 20.6 °C | +1.1 °C | 9 mm | -78 mm |
| Dec | 16.7 °C | +0.7 °C | 58 mm | -46 mm |
The year's extremes
What was the weather like that day?
Your birthday, a wedding, a memorable trip: discover the actual weather for any date since 1940.
Frequently asked questions
What is the climate of Slidell?
Slidell has a humid subtropical climate (Köppen Cfa). Over 1940-2025, the average annual temperature is 20.2 °C and it receives 1,266 mm of precipitation per year.
What is the hottest day ever recorded in Slidell?
The hottest day measured in Slidell between 1940 and 2025 was 26 August 1943, reaching 36.8 °C.
What is the coldest day in Slidell?
The coldest day measured in Slidell between 1940 and 2025 was 21 January 1985, at -10.8 °C.
Does it snow in Slidell?
Almost never: Slidell sees virtually no snow, with about 3 frost days per year.
Has the climate of Slidell warmed?
Yes: Slidell warmed by +1.0 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Slidell?
The wettest day measured in Slidell between 1940 and 2025 was 29 August 2012, with 291 mm of rain in 24 hours.
What was the windiest day in Slidell?
The windiest day measured in Slidell between 1940 and 2025 was 29 August 2005, with winds reaching 104.5 km/h.
What is the warmest month in Slidell?
The warmest month in Slidell is July (27.7 °C on average); the coldest is January (11.3 °C).
How much does it rain in Slidell?
Slidell receives on average 1,266 mm of precipitation per year, spread over about 134 rainy days.
Is it sunny in Slidell?
Slidell gets on average 9.8 hours of sunshine per day, roughly 3,577 hours per year over 1940-2025.
What is the biggest single-day snowfall in Slidell?
The heaviest 24-hour snowfall measured in Slidell between 1940 and 2025 was 21 January 2025, with 8.5 cm.
Are there tropical nights in Slidell?
Yes: Slidell has on average 164 tropical nights per year (temperature staying above 20 °C), over 1940-2025.
What was the most extreme apparent temperature in Slidell?
In Slidell, between 1940 and 2025, the highest apparent temperature reached 43.4 °C on 2 August 2010, and the lowest was -18.7 °C on 23 December 1989.
Compare Slidell with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Slidell