Sioux City, IA

Iowa · Records since 1889–2026

☁️ 82°F Feels like 85°
Currently in Sioux City
As of 1:15 PM CDT

Records for September 7

🔥 Record High

101°F

September 7, 1971

+22° from 79° normal

❄ Record Low

36°F

September 7, 2025

-19° from 55° normal
🌞 Normal high: 79°F 🌑 Normal low: 55°F 1991–2020 normals

All-Time Records — Sioux City

🔥
111°F
Hottest Day Ever
Jul 11, 1939
❄
-35°F
Coldest Day Ever
Jan 12, 1912
🌧
5.50"
Wettest Day Ever
Jul 17, 1972
☃
20.0"
Most Snow in One Day
Apr 10, 1913

Top 10 Record Highs — September 7

# Temp Date
🏆 101°F September 7, 1971
2 101°F September 7, 1931
3 96°F September 7, 1922
4 95°F September 7, 1978
5 95°F September 7, 1976
6 95°F September 7, 1940
7 95°F September 7, 1939
8 95°F September 7, 1913
9 94°F September 7, 2002
10 94°F September 7, 1959

Top 5 Record Lows — September 7

# Temp Date
🥶 36°F September 7, 2025
2 38°F September 7, 1986
3 40°F September 7, 1956
4 41°F September 7, 1918
5 42°F September 7, 2008
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 1889–2026. Climate normals represent the 1991–2020 average.

Heat Wave Summary — Sioux City

threshold: 94°F (90th percentile of historical Jun–Aug highs)
4.4
Avg heat wave length
days (historical)
100°
Avg peak temp
during heat waves
18
Dangerous nights 2026
Overnights ≥ 70°F
1
Heat waves 2026
so far

2026 Daily High Temperature vs Normal

Year to date
Above normal Below normal

162 of 249 days with data were above the 1991–2020 normal high for their date.

Days ≥ 90°F Per Year

1889–2026
34
2026 so far
28
Avg/year 1970–2025
30
Avg/year (last 10 complete)
73
Most in a year (1936)

Average Daily High by Decade

Full year · complete decades only

Longest Heat Waves — Sioux City

# Dates Days Peak Avg High Avg Overnight Low
🏆 Jul 9, 1901 – Jul 27, 1901 19 106°F (Jul 21) 100°F 73°F
2 Jul 3, 1936 – Jul 19, 1936 17 111°F (Jul 4) 104°F 78°F
3 Jul 25, 1955 – Aug 5, 1955 12 107°F (Jul 31) 100°F 74°F
4 Aug 8, 1936 – Aug 18, 1936 11 105°F (Aug 15) 99°F 74°F
5 Jul 16, 1934 – Jul 25, 1934 10 107°F (Jul 20) 102°F 76°F
6 Jul 17, 1974 – Jul 26, 1974 10 103°F (Jul 18) 99°F 72°F
7 Jun 25, 1990 – Jul 3, 1990 9 104°F (Jul 3) 96°F 72°F
8 Jul 2, 1937 – Jul 10, 1937 9 103°F (Jul 7) 97°F 72°F
9 Jul 21, 1936 – Jul 28, 1936 8 108°F (Jul 25) 101°F 74°F
10 Jul 17, 1940 – Jul 24, 1940 8 107°F (Jul 24) 100°F 73°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
48.1
Avg / summer
1970–2020
72
Most in a summer
1936

Above-Normal Summer Nights Per Year

Average June–August Low by Decade

Overnight lows · complete decades only

Precipitation

Actual vs. 1991–2020 full-month and full-season normals

17.56"
2026 YTD
Normal: 22.60"
-5.04"
0.61"
September so far
September normal: 2.84"
-2.23"
5
2026 heavy rain days
Days with ≥ 1.0"

2026 Accumulation vs. Normal

Running total since Jan 1 against the normal pace for the same date · Sioux City is 5.04" behind the normal pace

Monthly Precipitation — Last 24 Months

Blue = actual · dashed line = monthly normal

Annual Precipitation Per Year (1889–2026)

Blue = above average · tan = below average · gold = 2026 (partial)
Since 1889, annual totals have trended +0.35" per decade, about +4.7" across the record.

Heavy Rain Days Per Year (≥ 1.0")

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

Month in Review — August 2026

72.8°F

Average temperature · August 2026

218th-warmest month on record

71st-warmest August of 138 on record

+0.6° vs. 72.2° average (1991–2020)
87.2°F
Warmest month ever
July 1936
81.0°F
Warmest August ever
1936
3
Days ≥ 90°F
in August
101°F
Hottest of 2026
Jul 20

Longest 90°F Streak in August

2 consecutive days with highs of at least 90°F (Aug 10–11, 2026, peaking at 94°F)

Ties the longest August streak since 2025 (1 year). The August record is 15 days, set in 1955.

100°F Milestone

Sioux City reached 101°F in 2026 — the first time it hit 100°F since 2023 (3 years).

Average August Temperature by Year

1889–2026 · 2026 highlighted

Precipitation — August 2026

Month total against the 1991–2020 average and every other August on record

3.85"
Total precipitation
August 2026
-0.09"
vs. average
Normal: 3.94" · 98% of normal
43rd-wettest
August rank
of 138 on record
10.12"
Wettest August ever
2014 · driest 0.12" (1971)

August Precipitation by Year

1889–2026 · 2026 highlighted · trend +0.08" per decade (wetter since 1889)

Wettest Augusts on Record

# Year Total
1 2014 10.12"
2 2007 9.07"
3 2017 8.16"
4 1951 7.75"
5 1923 7.63"
6 1937 7.09"
7 1912 7.03"
8 1961 7.00"
9 2006 6.98"
10 1993 6.43"

Driest Augusts on Record

# Year Total
1 1971 0.12"
2 1976 0.30"
3 1938 0.59"
4 1955 0.61"
5 1997 0.63"
6 1947 0.63"
7 1925 0.71"
8 1984 0.79"
9 1896 0.86"
10 1930 0.89"

Warmest Augusts on Record

# Year Avg Temp
1 1936 81.0°F
2 1983 80.9°F
3 1947 80.7°F
4 1937 80.4°F
5 1955 79.6°F
6 1938 78.1°F
7 1959 77.5°F
8 1900 77.2°F
9 1913 77.1°F
10 1973 77.1°F

Warmest Months on Record (Any Month)

# Month Avg Temp
1 July 1936 87.2°F
2 July 1935 82.9°F
3 July 1901 82.7°F
4 July 1955 81.5°F
5 July 1974 81.3°F
6 July 1916 81.1°F
7 August 1936 81.0°F
8 August 1983 80.9°F
9 August 1947 80.7°F
10 July 1930 80.5°F

Nearby Stations — August 2026

How the same month ranked at the closest reporting stations

Station Avg Temp August Rank
Sioux City, IA 72.8°F 71st of 138
Norfolk, NE 73.4°F 70th of 134
Sioux Falls, SD 73.6°F 27th of 132
Spencer, IA 70.0°F 69th of 112
Omaha, NE 76.5°F 44th of 156
About this data. Monthly averages are the mean of daily average temperatures, computed from NOAA Threadex records via RCC ACIS. Months missing more than three days of observations are excluded from the rankings, so the in-progress month never appears. Rankings cover 1,642 complete months on record. Precipitation totals sum the daily reports for the month, with trace amounts counted as zero. A month missing any day of precipitation data is left out entirely (an unreported day is unreported rain), so the precipitation ranking covers 138 complete Augusts. Normals are the 1991–2020 mean for the same calendar month. Trend lines are a least-squares fit across every year shown.

Fall in Review — Fall 2026

September 1 – November 30, 2026

Fall 2026 is still under way. Season totals and rankings appear once November closes; the markers below update as they happen.

Summer to Winter — 2026

Each turning point of the season against its 1991–2020 normal date, with the earliest and latest on record

Marker 2026 Normal vs. normal Earliest Latest Drift
Last 90°F day
The final day of summer heat
 Sep 5
so far
 Sep 15 Jul 23, 1915 Oct 15, 1958 +0.8 d/decade
Last 80°F day
The last genuinely warm afternoon
 Sep 6
so far
 Oct 13 Sep 17, 1890 Nov 8, 2006 +0.2 d/decade
First high below 50°F
The first afternoon that stays cold
 not yet Oct 18 Sep 14, 1903 Nov 18, 2016 +0.7 d/decade
First 32°F freeze
Growing season over
 not yet Oct 2 Sep 13, 1902 Nov 8, 1900 -0.5 d/decade
First 28°F hard freeze
Cold enough to end tender growth
 not yet Oct 15 Sep 22, 1995 Nov 21, 1931 -0.7 d/decade
First 20°F night
Winter cold arriving
 not yet Nov 4 Oct 7, 2012 Dec 6, 1998 -0.4 d/decade
First measurable snow
0.1" or more in a day
 not yet Nov 11 Sep 30, 1961 Dec 25, 1933 -0.3 d/decade

Drift is a least-squares fit across every year on record. Positive means the marker has been arriving later.

First Freeze by Year

The first 32°F night of each autumn since 1889 · trending -0.5 days earlier per decade

156
Normal length
1991–2020 average
213
Longest on record
1905
123
Shortest on record
1997

Growing Season Length by Year

Days between the last spring freeze and the first fall freeze · trending -0.8 days shorter per decade

Fall Average Temperature by Year

1889–2025 · 2026 highlighted

Fall Precipitation by Year

1889–2025 · 2026 highlighted · trend +0.06" per decade (wetter since 1889)

About this data. Fall is meteorological autumn, September 1 through November 30, the window NOAA uses for seasonal statistics. Seasonal temperature is the day-weighted mean of the three monthly means; precipitation is their sum, and a season missing any of the three months is left out of the rankings. Freeze, heat and snow markers come from daily NOAA Threadex observations via RCC ACIS: freezes and snow are the first occurrence on or after July 1, and the last 90°F and 80°F days are the final ones anywhere in the calendar year. Growing season counts the freeze-free days between the last spring 32°F and the first fall 32°F.
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