Climate normals, framed for cooling
When is AC season in New Orleans?
Normal highs stay at or above 80°F from April 23 to October 18 — 179 days, about 6 months. This calendar shows when the heat arrives, when the air turns muggy, and what the long-term record says your AC is up against.
Built from the official 1991–2020 climate normals, accessed 2026-10-16. The normals change next at the ~2031 release.
Right now at the airport
with a dew point of
The calendar
These dates come from the 30-year daily normals for New Orleans International Airport. A normal is an average, not a forecast: any one year will run earlier or later.
| Normal highs reach | First day | Last day | Days |
|---|---|---|---|
| 80°F or hotter | April 23 | October 18 | 179 |
| 85°F or hotter | May 15 | October 1 | 140 |
| 90°F or hotter | June 13 | September 3 | 83 |
Normal highs top out at 91.7°F, a plateau that holds from July 26through August 10. The 90°F stretch — June 13 toSeptember 3 — is when cooling demand peaks; the months before it are the calm part of the calendar.
Cooling load by month
Cooling degree days (CDD) measure how much cooling the weather demands: each degree the daily average runs above 65°F adds one degree day. The New Orleans airport normals total 3,206 CDD a year — and July and August together carry more load than November through April combined.
| Month | Cooling degree days | Mean dew point |
|---|---|---|
| January | 18 | 44.8°F |
| February | 32 | 48.1°F |
| March | 81 | 53.2°F |
| April | 180 | 59.2°F |
| May | 378 | 66.1°F |
| June | 520 | 71.9°F |
| July | 587 | 73.9°F |
| August | 587 | 73.9°F |
| September | 474 | 70.2°F |
| October | 252 | 61.4°F |
| November | 67 | 52.4°F |
| December | 30 | 47.6°F |
The muggy season
Temperature is only half the story here. From May 31 to September 19 —112 straight days in the normals — the mean dew point at the airport sits at 70°F or higher. The National Weather Service calls anything at or above 65°F oppressive.
That moisture is real work for an air conditioner. Part of your system’s capacity goes to pulling water out of the air before it can lower the temperature, which is why muggy days mean longer run times, and why a house can read 72°F and still feel clammy.
Airport vs. the city
These normals describe the airport in Kenner. For daily highs, the Audubon station uptown runs hotter: its normal high on July 1 is 93.4°F against 91°F at MSY, and its hottest normal stretch reaches 94.5°F. The airport highs on this page are the cooler of the two stations; the dew point figures are airport-only.
Get the data
Methodology
Every number on this page is computed from the NCEI U.S. Climate Normals 1991–2020 for New Orleans International Airport (GHCN station USW00012916) and New Orleans Audubon (USW00012930), fetched once from the NCEI Access Data Service and checked into this site’s repository. The page and the CSV download are generated from that committed data in code — nothing is typed in by hand.
- Season spans are the first and last calendar days whose normal daily high (DLY-TMAX-NORMAL, from the normals-daily-1991-2020 dataset) is at or above each threshold. All three spans are unbroken in the normals.
- Monthly and annual cooling degree days (base 65°F) come from NOAA’s monthly normals product (MLY-CLDD-NORMAL, normals-monthly-1991-2020). Summing the daily normals instead lands about 3 CDD higher per year because NOAA computes the two products separately; the CSV download carries the daily values.
- Dew point statistics come from the hourly dew point normals (HLY-DEWP-NORMAL) for MSY, which NCEI publishes as a 365-day cycle (no February 29). A day’s mean is the average of its 24 hourly normals. Audubon does not factor into the dew point figures.
- The build refuses to publish if the data carries NCEI’s missing-value sentinels or an unexpected number of days, hours, or months.
- Normals are 30-year averages that describe climatology, not a forecast for any particular year.
- The live strip reads the latest NWS observation for KMSY (KNEW as fallback), refreshed every 10 minutes. If the reading is more than two hours old or the feed is down, the strip does not show, and this page falls back to the normals you see here. Dew point comfort wording follows the published NWS scale.
Sources
- NCEI U.S. Climate Normals 1991–2020 (daily and hourly normals, stations USW00012916 and USW00012930) — accessed 2026-10-16
- NWS real-time observations for KMSY, api.weather.gov — accessed 2026-10-16
- NWS dew point comfort scale — accessed 2026-10-16