Wilmington, DE

Delaware · Records since 1894–2026

☁️ 81°F
Currently in Wilmington
As of 2:30 PM EDT

Records for September 11

🔥 Record High

100°F

September 11, 1983

+20° from 80° normal

❄ Record Low

39°F

September 11, 1917

-22° from 61° normal
🌞 Normal high: 80°F 🌑 Normal low: 61°F 1991–2020 normals

All-Time Records — Wilmington

🔥
107°F
Hottest Day Ever
Aug 7, 1918
❄
-15°F
Coldest Day Ever
Feb 9, 1934
🌧
8.29"
Wettest Day Ever
Sep 16, 1999
☃
22.0"
Most Snow in One Day
Jan 7, 1996

First & Last Dates — Wilmington

How early and how late each seasonal turning point has ever arrived, across the full period of record

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Range ever recorded Normal date (1991–2020)
234 days
Longest growing season
2005
144 days
Shortest growing season
1947
208 days
Normal growing season
1991–2020 average

Top 10 Record Highs — September 11

# Temp Date
🏆 100°F September 11, 1983
2 94°F September 11, 1964
3 93°F September 11, 1931
4 91°F September 11, 2013
5 91°F September 11, 1989
6 90°F September 11, 2019
7 90°F September 11, 1961
8 90°F September 11, 1896
9 89°F September 11, 1925
10 89°F September 11, 1895

Top 5 Record Lows — September 11

# Temp Date
🥶 39°F September 11, 1917
2 44°F September 11, 1924
3 46°F September 11, 1949
4 47°F September 11, 1958
5 47°F September 11, 1932
About this data — Records are sourced from the NOAA Threadex dataset via RCC ACIS, a quality-controlled record for long-term climate stations. Threadex adjusts for station relocations and observation-time changes, making records comparable across all years since 1894–2026. Climate normals represent the 1991–2020 average.

Heat Wave Summary — Wilmington

threshold: 92°F (90th percentile of historical Jun–Aug highs)
4.2
Avg heat wave length
days (historical)
97°
Avg peak temp
during heat waves
37
Dangerous nights 2026
Overnights ≥ 70°F
2
Heat waves 2026
so far

Days ≥ 90°F Per Year

1894–2026
30
2026 so far
21
Avg/year 1970–2025
29
Avg/year (last 10 complete)
59
Most in a year (1895)

Average Daily High by Decade

Full year · complete decades only

Longest Heat Waves — Wilmington

# Dates Days Peak Avg High Avg Overnight Low
🏆 Aug 3, 1896 – Aug 13, 1896 11 103°F (Aug 6) 99°F 75°F
2 Aug 26, 1953 – Sep 5, 1953 11 101°F (Aug 30) 97°F 69°F
3 Jul 25, 1894 – Aug 3, 1894 10 101°F (Jul 28) 96°F 73°F
4 Jul 12, 1894 – Jul 21, 1894 10 98°F (Jul 13) 95°F 72°F
5 Aug 5, 1895 – Aug 12, 1895 8 101°F (Aug 11) 96°F 71°F
6 Aug 3, 1930 – Aug 10, 1930 8 98°F (Aug 5) 95°F 71°F
7 Jul 19, 1987 – Jul 26, 1987 8 98°F (Jul 21) 95°F 73°F
8 Jul 7, 1993 – Jul 14, 1993 8 98°F (Jul 8) 96°F 76°F
9 Jul 28, 2002 – Aug 4, 2002 8 98°F (Aug 1) 95°F 72°F
10 Jul 25, 1940 – Jul 31, 1940 7 102°F (Jul 31) 97°F 71°F

Heat Waves Per Year

Warm Summer Nights (Jun–Aug)

Nights where the overnight low exceeded the 1991–2020 normal low

52
2026 total
above-normal nights
44.4
Avg / summer
1970–2020
67
Most in a summer
1973

Above-Normal Summer Nights Per Year

Average June–August Low by Decade

Overnight lows · complete decades only

Precipitation

Annual totals and trend across the full period of record · see this year's standing →

Monthly Precipitation — Last 24 Months

Blue = actual · dashed line = monthly normal

Annual Precipitation Per Year (1894–2026)

Blue = above average · tan = below average · gold = 2026 (partial)
Since 1894, annual totals have trended +0.26" per decade, about +3.4" across the record.

Heavy Rain Days Per Year (≥ 1.0")

Compare year-to-year changes in days with heavy rainfall (≥ 1.0")

This Year — 2026

How Wilmington is tracking against normal, year to date

Daily High Temperature vs Normal

Above normal Below normal

130 of 253 days with data were above the 1991–2020 normal high for their date.

Precipitation, Year to Date

32.17"
2026 YTD
Normal: 31.71"
+0.46"
1.73"
September so far
September normal: 4.38"
-2.65"
7
2026 heavy rain days
Days with ≥ 1.0"

Accumulation vs. Normal

Running total since Jan 1 against the normal pace for the same date · Wilmington is 0.46" ahead of the normal pace

Period Review — Jun 12 – Sep 10, 2026

Any window, evaluated against every other year on record — 91 days

Quick picks: Last 7 days Last 30 days Last 90 days This month
Seasons: Spring (Mar–May) Summer (Jun–Aug) Fall (Sep–Nov)
77.1°F
Average temperature
9th-warmest of 113
+1.6°
vs. average
Normal: 75.5°F (1991–2020)
18.77"
Precipitation
10th-wettest of 116
+6.24"
vs. average
Normal: 12.53" · 150% of normal

Average Temperature by Year — Jun 12 – Sep 10

1894–2026 · 2026 highlighted · trend +0.21° per decade (warming since 1894)

Precipitation by Year — Jun 12 – Sep 10

1896–2026 · 2026 highlighted · trend -0.05" per decade (drier since 1896)

Warmest Jun 12 – Sep 10 on Record

# Year Avg Temp
1 2010 77.8°F
2 1894 77.8°F
3 1993 77.8°F
4 2016 77.7°F
5 1973 77.2°F
6 2012 77.2°F
7 2022 77.1°F
8 2023 77.1°F
9 2026 77.1°F
10 2019 77.0°F

Coolest Jun 12 – Sep 10 on Record

# Year Avg Temp
1 1927 70.1°F
2 1946 70.9°F
3 1962 71.9°F
4 1940 71.9°F
5 1950 72.2°F
6 1924 72.2°F
7 1920 72.3°F
8 1926 72.4°F
9 1958 72.4°F
10 1965 72.5°F

Wettest Jun 12 – Sep 10 on Record

# Year Total
1 1919 25.97"
2 1911 25.54"
3 2023 24.62"
4 1945 24.61"
5 2011 23.30"
6 1906 22.27"
7 1938 20.39"
8 1942 20.19"
9 2006 19.27"
10 2026 18.77"

Driest Jun 12 – Sep 10 on Record

# Year Total
1 1966 4.67"
2 1930 4.94"
3 1964 5.83"
4 1963 6.70"
5 2005 7.08"
6 1983 7.12"
7 1953 7.16"
8 1962 7.24"
9 1980 7.29"
10 2007 7.30"
About this data. Pick any start and end date and this becomes the same kind of review as the Month and Fall tabs, just for exactly the window you asked for — the generalized version of the same engine, evaluated across every year on record. Average temperature is the mean of each day's (high + low) / 2; precipitation is the sum of daily totals. A year missing more than about a fifth of the window's days is excluded from the temperature ranking; any missing day excludes a year from the precipitation ranking, since an unreported day is unreported rain. Ranges that cross from December into January aren't supported yet. Normals are the 1991–2020 mean for the same window.
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