Riverside, CA

California · Records since 1893–2026

☀️ 93°F Feels like 98°
Currently in Riverside
As of 11:30 AM PDT

Records for September 11

🔥 Record High

108°F

September 11, 1955

+15° from 93° normal

❄ Record Low

45°F

September 11, 1952

-18° from 63° normal
🌞 Normal high: 93°F 🌑 Normal low: 63°F 1991–2020 normals

All-Time Records — Riverside

🔥
118°F
Hottest Day Ever
Jul 6, 2018
❄
19°F
Coldest Day Ever
Jan 7, 1950
🌧
4.42"
Wettest Day Ever
Mar 4, 1938
☃
2.0"
Most Snow in One Day
Jan 11, 1949

First & Last Dates — Riverside

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)
356 days
Longest growing season
1974
203 days
Shortest growing season
1906

Top 10 Record Highs — September 11

# Temp Date
🏆 108°F September 11, 1955
2 107°F September 11, 1990
3 107°F September 11, 1983
4 107°F September 11, 1971
5 107°F September 11, 1948
6 106°F September 11, 1963
7 105°F September 11, 1979
8 105°F September 11, 1960
9 105°F September 11, 1918
10 103°F September 11, 1946

Top 5 Record Lows — September 11

# Temp Date
🥶 45°F September 11, 1952
2 45°F September 11, 1931
3 45°F September 11, 1901
4 46°F September 11, 1950
5 46°F September 11, 1949
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 1893–2026. Climate normals represent the 1991–2020 average.
3
days
🔥 Heat Wave in Progress
3 consecutive days at or above 101°F · since September 8
Heat wave in progress (3+ days ≥ 101°F)

Heat Wave Summary — Riverside

threshold: 101°F (90th percentile of historical Jun–Aug highs)
4.2
Avg heat wave length
days (historical)
107°
Avg peak temp
during heat waves
30
Dangerous nights 2026
Overnights ≥ 70°F
5
Heat waves 2026
so far

Days ≥ 90°F Per Year

1893–2026
92
2026 so far
95
Avg/year 1970–2025
106
Avg/year (last 10 complete)
146
Most in a year (1917)

Average Daily High by Decade

Full year · complete decades only

Longest Heat Waves — Riverside

# Dates Days Peak Avg High Avg Overnight Low
🏆 Jul 22, 1980 – Aug 1, 1980 11 109°F (Jul 29) 103°F 70°F
2 Aug 19, 2026 – Aug 29, 2026 11 107°F (Aug 26) 103°F 73°F
3 Aug 12, 2020 – Aug 21, 2020 10 109°F (Aug 15) 104°F 72°F
4 Aug 27, 1995 – Sep 5, 1995 10 108°F (Sep 2) 104°F 66°F
5 Aug 26, 2009 – Sep 4, 2009 10 108°F (Aug 27) 104°F 69°F
6 Aug 12, 1992 – Aug 21, 1992 10 107°F (Aug 17) 105°F 72°F
7 Sep 10, 1913 – Sep 18, 1913 9 111°F (Sep 17) 105°F 58°F
8 Sep 8, 1979 – Sep 16, 1979 9 111°F (Sep 9) 105°F 65°F
9 Aug 30, 2022 – Sep 7, 2022 9 110°F (Sep 4) 107°F 75°F
10 Aug 6, 2012 – Aug 14, 2012 9 106°F (Aug 6) 104°F 73°F

Heat Waves Per Year

Warm Summer Nights (Jun–Aug)

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

64
2026 total
above-normal nights
33.9
Avg / summer
1970–2020
68
Most in a summer
2022

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 (1893–2026)

Blue = above average · tan = below average · gold = 2026 (partial)
Since 1893, annual totals have trended -0.25" per decade, about -3.2" 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 Riverside is tracking against normal, year to date

Daily High Temperature vs Normal

Above normal Below normal

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

Precipitation, Year to Date

3.93"
2026 YTD
Normal: 6.88"
-2.95"
0.36"
September so far
September normal: 0.11"
+0.25"
0
2026 heavy rain days
Days with ≥ 1.0"

Accumulation vs. Normal

Running total since Jan 1 against the normal pace for the same date · Riverside is 2.95" behind the normal pace

Period Review — Sep 1 – Sep 10, 2026

Any window, evaluated against every other year on record — 10 days

Quick picks: Last 7 days Last 30 days Last 90 days This month
Seasons: Spring (Mar–May) Summer (Jun–Aug) Fall (Sep–Nov)
79.8°F
Average temperature
34th-warmest of 123
-0.9°
vs. average
Normal: 80.7°F (1991–2020)
0.36"
Precipitation
4th-wettest of 121
+0.34"
vs. average
Normal: 0.02" · 1800% of normal

Average Temperature by Year — Sep 1 – Sep 10

1893–2026 · 2026 highlighted · trend +0.83° per decade (warming since 1893)

Precipitation by Year — Sep 1 – Sep 10

1901–2026 · 2026 highlighted · trend +0.01" per decade (wetter since 1901)

Warmest Sep 1 – Sep 10 on Record

# Year Avg Temp
1 2024 89.2°F
2 2022 89.0°F
3 1955 86.0°F
4 2013 85.3°F
5 1997 85.0°F
6 1984 84.6°F
7 2017 83.8°F
8 2007 83.5°F
9 1995 83.3°F
10 1988 83.1°F

Coolest Sep 1 – Sep 10 on Record

# Year Avg Temp
1 1912 66.0°F
2 1901 67.8°F
3 1942 67.9°F
4 1916 68.8°F
5 1933 69.4°F
6 1973 69.5°F
7 1951 70.2°F
8 1914 70.2°F
9 1905 70.5°F
10 1906 70.5°F

Wettest Sep 1 – Sep 10 on Record

# Year Total
1 1976 1.37"
2 1978 1.15"
3 1963 0.62"
4 2026 0.36"
5 2023 0.31"
6 1982 0.30"
7 2014 0.23"
8 2017 0.22"
9 1939 0.21"
10 1958 0.19"

Driest Sep 1 – Sep 10 on Record

# Year Total
1 2025 0.00"
2 2024 0.00"
3 2021 0.00"
4 2020 0.00"
5 2018 0.00"
6 2016 0.00"
7 2013 0.00"
8 2012 0.00"
9 2010 0.00"
10 2009 0.00"
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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