Wilmington weather in September: Wilmington, Delaware: normal highs, lows, rain and records for September
Wilmington in September has a normal high of 79°F and a normal low of 59°F, a daily mean of 69°F, falling from 83°F on the 1st to 73°F by the 30th. Measurable precipitation falls on 9 days in a normal September, 4.38 inches in all. (NOAA 1991-2020 normals)
In metric: a normal high of 26°C and low of 15°C, 111 mm of precipitation in September.
- NOAA stationWilmington Airport
- Station IDUSW00013781
- Location39.67°N 75.60°W
- Elevation79 ft (24 m)
- From the center6 miles
- Population73,176
- Jan 41° 26°
- Feb 44° 27°
- Mar 53° 34°
- Apr 64° 44°
- May 74° 53°
- Jun 82° 63°
- Jul 87° 68°
- Aug 85° 67°
- Sep 79° 59°
- Oct 67° 47°
- Nov 56° 37°
- Dec 46° 30°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
How warm is Wilmington in September?
The normal high is 79°F and the normal low 59°F, for a daily mean of 68.9°F. September is 6.9°F cooler than August and 11.7°F warmer than October. September is the 4th warmest month of the year in Wilmington and the 3rd wettest. Across the month the normal high falls 10°F, from 83°F on September 1 to 73°F on September 30. From one year to the next September's mean temperature typically moves about 2.2°F either way (NOAA's standard deviation), so roughly two Septembers in three average between 67°F and 71°F.
Bars above: each day's normal high to low. Columns below: the chance of 0.01 inch or more of precipitation that day, on a scale of 0 to 100% (highest 31%).
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in |
|---|---|---|---|---|
| September 1 | 83°F | 64°F | 27% | 18% |
| September 8 | 81°F | 62°F | 27% | 18% |
| September 15 | 79°F | 60°F | 28% | 18% |
| September 22 | 76°F | 57°F | 30% | 19% |
| September 30 | 73°F | 54°F | 31% | 19% |
Every day of September: normal high, low and chance of precipitation (warmest afternoon September 1, coldest night September 30)
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in | Daylight |
|---|---|---|---|---|---|
| September 1 | 83°F | 64°F | 27% | 18% | 13 h 10 min |
| September 2 | 83°F | 64°F | 27% | 18% | 13 h |
| September 3 | 82°F | 63°F | 27% | 18% | 13 h |
| September 4 | 82°F | 63°F | 27% | 18% | 13 h |
| September 5 | 82°F | 63°F | 27% | 18% | 13 h |
| September 6 | 82°F | 63°F | 27% | 18% | 12 h 50 min |
| September 7 | 81°F | 62°F | 27% | 18% | 12 h 50 min |
| September 8 | 81°F | 62°F | 27% | 18% | 12 h 50 min |
| September 9 | 81°F | 62°F | 27% | 18% | 12 h 50 min |
| September 10 | 81°F | 61°F | 27% | 18% | 12 h 40 min |
| September 11 | 80°F | 61°F | 27% | 18% | 12 h 40 min |
| September 12 | 80°F | 61°F | 28% | 18% | 12 h 40 min |
| September 13 | 80°F | 60°F | 28% | 18% | 12 h 40 min |
| September 14 | 79°F | 60°F | 28% | 18% | 12 h 30 min |
| September 15 | 79°F | 60°F | 28% | 18% | 12 h 30 min |
| September 16 | 79°F | 59°F | 28% | 18% | 12 h 30 min |
| September 17 | 78°F | 59°F | 29% | 19% | 12 h 30 min |
| September 18 | 78°F | 59°F | 29% | 19% | 12 h 20 min |
| September 19 | 78°F | 58°F | 29% | 19% | 12 h 20 min |
| September 20 | 77°F | 58°F | 29% | 19% | 12 h 20 min |
| September 21 | 77°F | 58°F | 29% | 19% | 12 h 20 min |
| September 22 | 76°F | 57°F | 30% | 19% | 12 h 10 min |
| September 23 | 76°F | 57°F | 30% | 19% | 12 h 10 min |
| September 24 | 76°F | 56°F | 30% | 19% | 12 h 10 min |
| September 25 | 75°F | 56°F | 30% | 19% | 12 h 10 min |
| September 26 | 75°F | 55°F | 31% | 19% | 12 h |
| September 27 | 74°F | 55°F | 31% | 19% | 12 h |
| September 28 | 74°F | 55°F | 31% | 19% | 12 h |
| September 29 | 74°F | 54°F | 31% | 19% | 11 h 50 min |
| September 30 | 73°F | 54°F | 31% | 19% | 11 h 50 min |
- Normal high
- 79°FSeptember average
- Normal low
- 59°FSeptember average
- Precipitation
- 4.38 inmonth total
- Days with precipitation
- 90.01 inch or more
- Days at 90°F or more
- 2
- Daylight
- 13 h 10 min to 11 h 50 minSeptember 1 to September 30
- Days at 70°F or more
- 26
- Days at 80°F or more
- 13
- Sunshine
- 77%of clear-sky sunlight (NASA)
Source: NOAA NCEI 1991-2020 daily normals, station USW00013781; monthly normals. Daylight is computed from the place's latitude with NOAA's solar equations.
Does it rain in Wilmington in September?
On a given September day the chance of 0.01 inch or more is 29% on average, highest around September 28 (31%). In all, 4.38 in falls on 9 days of a normal September, 1 of them with an inch or more.
In a normal September in Wilmington, 2 days reach 90°F.
Source: NOAA NCEI 1991-2020 daily and monthly normals, station USW00013781.
What are the records for September in Wilmington?
The warmest September temperature on Wilmington's official record (since 1894) is 100°F, on September 3, 1953; the coldest is 32°F, on September 27, 1940. The wettest September brought 12.68 in (1999).
The September mean against the 1991-2020 normal of 68.9°F: 2021 70.3°F (+1.4), 2022 69.5°F (+0.6), 2023 69.4°F (+0.5), 2024 68.7°F (−0.2), 2025 71.1°F (+2.2), 2026 70.6°F (+1.7). 5 of 6 ran warmer than normal.
| September | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 70.3°F | +1.4°F | 5.36 in |
| 2022 | 69.5°F | +0.6°F | 2.85 in |
| 2023 | 69.4°F | +0.5°F | 5.08 in |
| 2024 | 68.7°F | −0.2°F | 0.33 in |
| 2025 | 71.1°F | +2.2°F | 1.86 in |
| 2026 | 70.6°F | +1.7°F | 5.73 in |
Source: records: ACIS, NWS threaded record ILGthr; recent months: ACIS, station USW00013781. Records and recent months use complete months only.
How does September in Wilmington compare across Delaware?
Across the 6 places PlainClimate covers in Delaware, September normal highs run from 79°F in Wilmington to 80°F in Lewes; Wilmington's is 79°F.
Source: NOAA NCEI 1991-2020 monthly normals for every station in the state.