Slidell, Louisiana climate: Normal weather by month, frost dates and records
Slidell's normal year runs from 41°F January nights to 91°F July afternoons, with 61.9 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 19.8°C, January lows of 5°C, July highs of 33°C, 1,572 mm of precipitation a year.
- NOAA stationSlidell Airport
- Station IDUSW00053865
- Location30.34°N 89.82°W
- Elevation27 ft (8 m)
- Population28,440
On October 14, the normal high in Slidell is 81°F and the normal low 58°F, and the chance of measurable rain or snow is 24%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Slidell.
- Jan 62° 41°
- Feb 66° 44°
- Mar 72° 50°
- Apr 78° 56°
- May 85° 64°
- Jun 90° 71°
- Jul 91° 73°
- Aug 91° 73°
- Sep 88° 69°
- Oct 81° 57°
- Nov 71° 47°
- Dec 64° 43°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like in Slidell each month?
July is the warmest month, with normal highs of 91°F; January the coldest, with normal lows of 41°F. The most precipitation falls in July (7.25 in), the least in October (3.72 in).
Each month has its own page with the day-by-day normals, the month's records and its recent years:
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 62°F | 41°F | 51.4°F | 5.57 | 10 | <1 | 8 | 10 h 20 min |
| February | 66°F | 44°F | 55.2°F | 4.14 | 9 | <1 | 5 | 11 h 10 min |
| March | 72°F | 50°F | 60.9°F | 4.94 | 8 | <1 | 2 | 12 h |
| April | 78°F | 56°F | 67.0°F | 5.21 | 9 | <1 | <1 | 12 h 50 min |
| May | 85°F | 64°F | 74.3°F | 5.46 | 8 | 5 | <1 | 13 h 40 min |
| June | 90°F | 71°F | 80.3°F | 6.11 | 12 | 17 | <1 | 14 h 10 min |
| July | 91°F | 73°F | 82.1°F | 7.25 | 14 | 22 | <1 | 14 h |
| August | 91°F | 73°F | 82.1°F | 6.96 | 14 | 23 | <1 | 13 h 20 min |
| September | 88°F | 69°F | 78.2°F | 4.14 | 10 | 13 | <1 | 12 h 20 min |
| October | 81°F | 57°F | 68.9°F | 3.72 | 7 | 1 | <1 | 11 h 30 min |
| November | 71°F | 47°F | 58.8°F | 3.89 | 8 | <1 | 2 | 10 h 40 min |
| December | 64°F | 43°F | 53.5°F | 4.49 | 9 | <1 | 7 | 10 h 10 min |
| Year (annual) | 78°F | 57°F | 67.7°F | 61.88 | 120 | 80 | 24 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | 17°C | 5°C | 10.8°C | 141 mm |
| February | 19°C | 7°C | 12.9°C | 105 mm |
| March | 22°C | 10°C | 16.1°C | 125 mm |
| April | 26°C | 13°C | 19.4°C | 132 mm |
| May | 29°C | 18°C | 23.5°C | 139 mm |
| June | 32°C | 22°C | 26.8°C | 155 mm |
| July | 33°C | 23°C | 27.8°C | 184 mm |
| August | 33°C | 23°C | 27.8°C | 177 mm |
| September | 31°C | 20°C | 25.7°C | 105 mm |
| October | 27°C | 14°C | 20.5°C | 94 mm |
| November | 22°C | 8°C | 14.9°C | 99 mm |
| December | 18°C | 6°C | 11.9°C | 114 mm |
NOAA publishes no 1991-2020 snowfall normal for this station. Slidell's own co-op station Slidell station does: 0 inches of snow in a normal year (see the other stations below).
Source: NOAA NCEI 1991-2020 monthly normals, station USW00053865; annual normals. Wet days: 0.01 inch or more; 90°F days and freezing nights: NOAA's day counts. Daylight: sunrise to sunset on the 15th, computed from the latitude.
When is the best weather to visit Slidell?
Normal highs sit between 65°F and 85°F in February, March, April, May, October and November. Of those, October has the fewest days with rain (7).
That is a measurement, not a recommendation: it counts the months whose normal afternoon high sits between 65°F and 85°F, where a light layer is enough by day.
Source: NOAA NCEI 1991-2020 monthly normals, station USW00053865.
When is the last frost in Slidell?
In Slidell, the last spring frost (32°F) comes after March 3 in half of years and after March 26 in one year in ten; the first autumn frost comes before November 21 in half of years and before November 4 in one year in ten.
Frost-free in half of yearsFrost in 1 to 9 years out of 10Frost most years
- Last spring frost, half of years after
- March 31 year in 10 after March 26; 9 in 10 after February 4
- First autumn frost, half of years before
- November 211 year in 10 before November 4; 9 in 10 before December 13
NOAA puts the median frost-free season at 263 days, and the season without a hard freeze (28°F) at 300 days.
A hard freeze (28°F) comes after February 14 in half of springs and before December 6 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Slidell in zone 9a across its 2 ZIP code areas (9a in 70458, the largest). By the map's own method, the average of each year's coldest night over 1991-2020, Slidell's NOAA station is in zone 9a: the coldest night of a typical year reaches 22°F (26 complete years).
Frost dates for every NOAA station in Louisiana · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USW00053865; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; the station zone: ACIS daily lows, 1991-2020. A 10% date means one year in ten has a frost after it in spring or before it in autumn.
What hardiness zone is each Slidell ZIP code in?
The USDA's 2023 map gives each ZIP code area one zone. Slidell's 2 ZIP code areas are all in zone 9a. Each ZIP's frost dates are in the frost tool.
Source: USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; ZIP areas in the place: Census Bureau 2020 ZCTA-to-place relationship file. A ZIP area counts when at least a tenth of its land (and 0.5 km²) lies in the place.
How hot and how cold does it get in Slidell?
In a normal year in Slidell, 80 days a year reach 90°F (1 of them 100°F or more), 24 nights fall to 32°F or colder and 120 days bring measurable precipitation.
- Days at 90°F or more
- 80a normal year
- Days at 100°F or more
- 1a normal year
- Nights at 32°F or colder
- 24a normal year
- Days that stay below freezing
- fewer than 1high of 32°F or less
- Days with 0.01 inch of precipitation
- 120a normal year
The highest temperature in this station's record (since 1994) is 108°F, on August 26, 2023; the lowest is 8°F, on January 22, 2025.
The wettest calendar year on that record is 2021, with 89.61 in.
Source: NOAA NCEI 1991-2020 annual normals, station USW00053865; records: ACIS (NOAA Regional Climate Centers), station USW00053865. Records use complete months only; a month missing more than three days is left out.
How sunny is Slidell?
Over a year 79% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Slidell, 4.7 kWh per square metre a day. October is the sunniest month (84%) and February the cloudiest (71%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 73% | 3.0 |
| February | 71% | 3.5 |
| March | 76% | 4.7 |
| April | 80% | 5.8 |
| May | 83% | 6.4 |
| June | 80% | 6.2 |
| July | 78% | 5.9 |
| August | 80% | 5.6 |
| September | 83% | 5.2 |
| October | 84% | 4.5 |
| November | 81% | 3.5 |
| December | 72% | 2.7 |
Source: NASA POWER solar climatology, 2001-2020 (CERES SYN1deg). Satellite-based, for the 1-degree cell (about 100 km across) around the station, so it describes the area rather than the airport.
How much heating and cooling does Slidell need?
A normal year in Slidell brings 1,612 heating degree days, 70% fewer than the median U.S. place (5,373), and 2,634 cooling degree days, 2.9 times the median (908). Two months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 6,753 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 434 | 11 |
| February | 296 | 21 |
| March | 177 | 50 |
| April | 57 | 117 |
| May | 4 | 294 |
| June | 0 | 459 |
| July | 0 | 530 |
| August | 0 | 529 |
| September | 1 | 398 |
| October | 49 | 171 |
| November | 219 | 34 |
| December | 374 | 19 |
| Year (annual) | 1,612 | 2,634 |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00053865. A degree day is one degree of a day's mean temperature below 65°F (heating) or above it (cooling); utilities use them to estimate energy use.
Has Slidell been warmer than normal lately?
2025 averaged 69.0°F, 1.3°F above the 1991-2020 normal of 67.7°F. 5 of the 5 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 69.2°F | +1.5°F | 89.61 |
| 2022 | 68.9°F | +1.2°F | 52.21 |
| 2023 | 71.3°F | +3.6°F | 41.99 |
| 2024 | 71.0°F | +3.3°F | 77.40 |
| 2025 | 69.0°F | +1.3°F | 46.15 |
Over 30 complete years from 1996 to 2025, the station's annual mean temperature rose at a fitted 6.6°F per century (+0.37°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USW00053865; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Slidell's climate compare?
Slidell is warmer than 36 of the other 64 places with their own NOAA record in Louisiana, and wetter than 39. Across the 7,247 U.S. stations with normals, its annual mean of 67.7°F is warmer than 93%.
In the Köppen classification computed from these normals, Slidell is Cfa: temperate, no dry season, hot summer. What the classes mean.
Places with the most similar year elsewhere
Measured month by month on the normal high, low and precipitation, among places of 20,000 or more people in other states:
Source: NOAA NCEI 1991-2020 normals for every station PlainClimate covers. Similarity: the root-mean-square difference of the 36 monthly figures, precipitation weighted so an inch counts like 6°F.
Which places near Slidell share this climate record?
3 places have no NOAA station with 1991-2020 normals of their own, and this station is the nearest full record. A place's own climate can differ from these figures, by several degrees where it sits much higher or lower than the station, nearer the coast, or inside a large city's heat; for the larger places the next nearest records are named with their yearly mean, so the spread around them is visible, and places of 50,000 or more have their own page with NOAA's gridded normals.
- Lacombe, LA6,883 people · 7 mi W
- Nicholson, MS2,523 people · 12 mi NE
- Pearlington, MS989 people · 14 mi SE
Source: Census Bureau 2024 Gazetteer (place centers) and Vintage 2024 population estimates. Distance and direction from the station to each place's center.
What do Slidell's other NOAA stations record?
One more NOAA station keeps 1991-2020 normals in or near Slidell. This page uses Slidell Airport; the other differs by site and elevation:
| Station | From this station | Elevation | Year | Jan low | Jul high | Precip. | Snow | Last frost |
|---|---|---|---|---|---|---|---|---|
| Slidell station USC00168539 | 6 mi SE | 10 ft | 67.6°F | 42°F | 90°F | 66.2 | 0 | February 24 |
Source: NOAA NCEI 1991-2020 normals for each station. Last frost: the median last spring date of 32°F.
Questions about Slidell's climate
What is the coldest month in Slidell?
January, with a normal high of 62°F and a normal low of 41°F. The warmest is July (91°F by day, 73°F at night).
Does it snow in Slidell?
Rarely. NOAA publishes no 1991-2020 snowfall normal for Slidell's NOAA station; Slidell's own co-op station Slidell station records 0 inches of snow in a normal year.
What is the rainiest month in Slidell?
July, with 7.25 in of precipitation in a normal year; the driest is October with 3.72 in.
What plant hardiness zone is Slidell in?
The USDA's 2023 map puts Slidell in zone 9a across its 2 ZIP code areas (9a in 70458, the largest). By the same method at Slidell's NOAA station, the coldest night of a typical year reaches 22°F (26 years, 1991-2020): zone 9a.
How late can frost come in Slidell?
In half of years the last 32°F night comes after March 3; in one year in ten it comes after March 26. Waiting until March 26 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Slidell in OctoberThis month day by day, its records and recent years
- Louisiana climateThe statewide normals and every place in the state
- Bay St. Louis, MS14 miles from this station, 65.6°F a year
- Picayune, MS15 miles from this station, 66.4°F a year
- Covington, LA21 miles from this station, 67.0°F a year
- Waveland, MS26 miles from this station, 67.0°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made