Riverside, CA
California · Records since 1893–2026
Records for September 26
🔥 Record High
September 26, 2010
+22° from 88° normal❄ Record Low
September 26, 1948
-21° from 60° normalAll-Time Records — Riverside
First & Last Dates — Riverside
How early and how late each seasonal turning point has ever arrived, across the full period of record
Top 10 Record Highs — September 26
| # | Temp | Date |
|---|---|---|
| 🏆 | 110°F | September 26, 2010 |
| 2 | 110°F | September 26, 1921 |
| 3 | 106°F | September 26, 2009 |
| 4 | 105°F | September 26, 1963 |
| 5 | 105°F | September 26, 1937 |
| 6 | 104°F | September 26, 1993 |
| 7 | 104°F | September 26, 1978 |
| 8 | 102°F | September 26, 2016 |
| 9 | 102°F | September 26, 1947 |
| 10 | 102°F | September 26, 1940 |
Top 5 Record Lows — September 26
| # | Temp | Date |
|---|---|---|
| 🥶 | 39°F | September 26, 1948 |
| 2 | 40°F | September 26, 1934 |
| 3 | 43°F | September 26, 1911 |
| 4 | 43°F | September 26, 1901 |
| 5 | 44°F | September 26, 1920 |
Heat Wave Summary — Riverside
threshold: 101°F (90th percentile of historical Jun–Aug highs)Days ≥ 90°F Per Year
1893–2026Average 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
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
169 of 267 days with data were above the 1991–2020 normal high for their date.
Precipitation, Year to Date
Accumulation vs. Normal
Running total since Jan 1 against the normal pace for the same date · Riverside is 3.00" behind the normal pace
Period Review — Sep 18 – Sep 25, 2026
Any window, evaluated against every other year on record — 8 days
Average Temperature by Year — Sep 18 – Sep 25
1893–2026 · 2026 highlighted · trend +0.54° per decade (warming since 1893)
Precipitation by Year — Sep 18 – Sep 25
1901–2025 · 2026 highlighted
Warmest Sep 18 – Sep 25 on Record
| # | Year | Avg Temp |
|---|---|---|
| 1 | 1939 | 85.4°F |
| 2 | 2015 | 82.0°F |
| 3 | 2009 | 81.6°F |
| 4 | 1991 | 81.4°F |
| 5 | 2012 | 80.8°F |
| 6 | 1984 | 80.0°F |
| 7 | 2002 | 79.3°F |
| 8 | 1922 | 79.3°F |
| 9 | 2003 | 79.1°F |
| 10 | 2020 | 78.9°F |
Coolest Sep 18 – Sep 25 on Record
| # | Year | Avg Temp |
|---|---|---|
| 1 | 1986 | 63.3°F |
| 2 | 1901 | 63.6°F |
| 3 | 1941 | 65.8°F |
| 4 | 1924 | 66.0°F |
| 5 | 1948 | 66.1°F |
| 6 | 1904 | 66.6°F |
| 7 | 1961 | 66.7°F |
| 8 | 1930 | 66.9°F |
| 9 | 1945 | 66.9°F |
| 10 | 1950 | 67.0°F |