Ontario, OR

Oregon · Records since 1945–2026

☀️ 74°F
Currently in Ontario
As of 12:00 PM MDT

Records for September 11

🔥 Record High

99°F

September 11, 1973

+14° from 85° normal

❄ Record Low

34°F

September 11, 2005

-16° from 50° normal
🌞 Normal high: 85°F 🌑 Normal low: 50°F 1991–2020 normals

All-Time Records — Ontario

🔥
113°F
Hottest Day Ever
Jul 12, 1967
❄
-25°F
Coldest Day Ever
Jan 22, 1962
🌧
1.59"
Wettest Day Ever
Sep 14, 1959
☃
10.0"
Most Snow in One Day
Jan 8, 1993

First & Last Dates — Ontario

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)
191 days
Longest growing season
2015
74 days
Shortest growing season
1976
159 days
Normal growing season
1991–2020 average

Top 10 Record Highs — September 11

# Temp Date
🏆 99°F September 11, 1973
2 99°F September 11, 1959
3 97°F September 11, 1990
4 95°F September 11, 1996
5 94°F September 11, 2015
6 94°F September 11, 2013
7 93°F September 11, 2011
8 93°F September 11, 1963
9 93°F September 11, 1960
10 93°F September 11, 1958

Top 5 Record Lows — September 11

# Temp Date
🥶 34°F September 11, 2005
2 36°F September 11, 1957
3 37°F September 11, 1988
4 38°F September 11, 1964
5 39°F September 11, 2010
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 1945–2026. Climate normals represent the 1991–2020 average.

Heat Wave Summary — Ontario

threshold: 102°F (90th percentile of historical Jun–Aug highs)
5.2
Avg heat wave length
days (historical)
107°
Avg peak temp
during heat waves
7
Dangerous nights 2026
Overnights ≥ 70°F
0
Heat waves 2026
so far

Days ≥ 90°F Per Year

1945–2026
63
2026 so far
64
Avg/year 1970–2025
69
Avg/year (last 10 complete)
94
Most in a year (1967)

Average Daily High by Decade

Full year · complete decades only

Longest Heat Waves — Ontario

# Dates Days Peak Avg High Avg Overnight Low
🏆 Jul 22, 1971 – Aug 14, 1971 24 110°F (Aug 8) 106°F 62°F
2 Jun 15, 1961 – Jun 26, 1961 12 108°F (Jun 17) 105°F 60°F
3 Aug 10, 1967 – Aug 20, 1967 11 109°F (Aug 19) 106°F 55°F
4 Jul 13, 1960 – Jul 22, 1960 10 112°F (Jul 19) 107°F 62°F
5 Jul 17, 1956 – Jul 26, 1956 10 107°F (Jul 23) 104°F 59°F
6 Jun 28, 2021 – Jul 7, 2021 10 107°F (Jun 30) 105°F 68°F
7 Jul 15, 1959 – Jul 23, 1959 9 111°F (Jul 21) 107°F 59°F
8 Jul 3, 1968 – Jul 11, 1968 9 108°F (Jul 4) 105°F 61°F
9 Jul 16, 2024 – Jul 24, 2024 9 108°F (Jul 22) 105°F 68°F
10 Jul 25, 1973 – Aug 2, 1973 9 107°F (Aug 2) 105°F 60°F

Heat Waves Per Year

Warm Summer Nights (Jun–Aug)

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

51
2026 total
above-normal nights
29.1
Avg / summer
1970–2020
72
Most in a summer
2021

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 (1945–2026)

Blue = above average · tan = below average · gold = 2026 (partial)
Since 1945, annual totals have trended +0.13" per decade, about +1.0" 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 Ontario is tracking against normal, year to date

Daily High Temperature vs Normal

Above normal Below normal

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

Precipitation, Year to Date

6.55"
2026 YTD
Normal: 6.34"
+0.21"
0.39"
September so far
September normal: 0.29"
+0.10"
1
2026 heavy rain days
Days with ≥ 1.0"

Accumulation vs. Normal

Running total since Jan 1 against the normal pace for the same date · Ontario is 0.21" ahead of the normal pace

Period Review — Aug 11 – Sep 10, 2026

Any window, evaluated against every other year on record — 31 days

Quick picks: Last 7 days Last 30 days Last 90 days This month
Seasons: Spring (Mar–May) Summer (Jun–Aug) Fall (Sep–Nov)
71.5°F
Average temperature
38th-warmest of 77
+0.1°
vs. average
Normal: 71.4°F (1991–2020)

Average Temperature by Year — Aug 11 – Sep 10

1945–2026 · 2026 highlighted · trend +0.40° per decade (warming since 1945)

Precipitation by Year — Aug 11 – Sep 10

1945–2025 · 2026 highlighted · trend -0.02" per decade (drier since 1945)

Warmest Aug 11 – Sep 10 on Record

# Year Avg Temp
1 2022 80.0°F
2 1967 78.3°F
3 2013 76.2°F
4 2023 75.9°F
5 2017 75.7°F
6 2025 75.6°F
7 1958 75.2°F
8 2019 75.0°F
9 1998 74.4°F
10 2020 73.9°F

Coolest Aug 11 – Sep 10 on Record

# Year Avg Temp
1 1954 65.9°F
2 1978 66.4°F
3 1968 66.5°F
4 1964 66.6°F
5 1993 66.8°F
6 1995 66.9°F
7 2010 67.1°F
8 1976 67.3°F
9 1989 67.3°F
10 1965 67.6°F
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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