44.014°N, 117.008°W · station ONOthr · 82 years of record
46°F
COLDEST SEP 4 SINCE 2021
forecast low · Sep 4
7-Day Forecast
NWS NDFD forecast low temperature for Ontario.
This Day in History
Every year's low on each of the next 7 forecast dates at Ontario — toggle a day below. The forecast line shows where it lands; the ringed bar is the coldest on record.
Ranks
#65 / 79
coldest Sep 2 in 79 yrs of record
Coldest Sep 2 ever
37°F
set in 1975
Mildest Sep 2 ever
70°F
set in 1949
Forecast low 57°F — 65th coldest Sep 2 of 79 years · record 37°F (1975) · coldest since 2024.
Ranks
#50 / 80
coldest Sep 3 in 80 yrs of record
Coldest Sep 3 ever
36°F
set in 1961
Mildest Sep 3 ever
63°F
set in 2013
Forecast low 53°F — 50th coldest Sep 3 of 80 years · record 36°F (1961) · coldest since 2021.
Ranks
#26 / 80
coldest Sep 4 in 80 yrs of record
Coldest Sep 4 ever
37°F
set in 1969
Mildest Sep 4 ever
69°F
set in 1950
Forecast low 46°F — 26th coldest Sep 4 of 80 years · record 37°F (1969) · coldest since 2021.
Ranks
#26 / 79
coldest Sep 5 in 79 yrs of record
Coldest Sep 5 ever
34°F
set in 1980
Mildest Sep 5 ever
65°F
set in 1978
Forecast low 47°F — 26th coldest Sep 5 of 79 years · record 34°F (1980) · coldest since 2021.
Ranks
#30 / 80
coldest Sep 6 in 80 yrs of record
Coldest Sep 6 ever
35°F
set in 1996
Mildest Sep 6 ever
65°F
set in 1998
Forecast low 49°F — 30th coldest Sep 6 of 80 years · record 35°F (1996) · coldest since 2021.
Ranks
#46 / 80
coldest Sep 7 in 80 yrs of record
Coldest Sep 7 ever
32°F
set in 1945
Mildest Sep 7 ever
65°F
set in 1963
Forecast low 51°F — 46th coldest Sep 7 of 80 years · record 32°F (1945) · coldest since 2016.
Ranks
#24 / 80
coldest Sep 8 in 80 yrs of record
Coldest Sep 8 ever
35°F
set in 1971
Mildest Sep 8 ever
63°F
set in 1998
Forecast low 47°F — 24th coldest Sep 8 of 80 years · record 35°F (1971) · coldest since 2015.
The hottest and coldest ever recorded at Ontario in each calendar month, and for the whole 1945–2026 record — with the year each was set.
Month
Record High
Record Low
Jan
64°FJan 9, 1953
-25°FJan 27, 1957
Feb
69°FFeb 29, 2024
-24°FFeb 4, 1989
Mar
85°FMar 30, 1966
9°FMar 11, 1948
Apr
94°FApr 24, 1977
17°FApr 6, 1956
May
103°FMay 29, 1986
25°FMay 1, 1946
Jun
109°FJun 28, 2015
31°FJun 18, 1973
Jul
113°FJul 12, 1967
34°FJul 5, 1986
Aug
113°FAug 4, 1961
33°FAug 28, 1960
Sep
104°FSep 1, 1967
24°FSep 19, 1965
Oct
93°FOct 3, 1963
9°FOct 30, 2019
Nov
74°FNov 7, 2006
-6°FNov 25, 1993
Dec
66°FDec 22, 1955
-23°FDec 10, 1972
All-time
113°FAug 4, 1961
-25°FJan 27, 1957
2026 Records So Far
Records set or tied at Ontario so far this year — through Aug 30.
Record Highs in 2026
2 broke
plus 1 tied — daily record highs set this year
Record Lows in 2026
0 broke
plus 0 tied — daily record lows set this year
Record Warm Nights & Cold Days
Two more daily records, kept separate from the rankings: the warmest a night has ever stayed (record high minimum) and the coldest a day has ever gotten (record low maximum) — the flip side of the usual record high and low.
Warmest low ever
81°F
record high minimum — the night it never cooled · Jun 30, 2015
Coldest high ever
-1°F
record low maximum — the day it never warmed · Dec 22, 1990
Month
Warmest low
Coldest high
Jan
45°FJan 4, 1966
3°FJan 23, 1962
Feb
48°FFeb 9, 2015
1°FFeb 6, 1989
Mar
55°FMar 13, 2003
23°FMar 1, 1993
Apr
57°FApr 28, 1987
43°FApr 7, 2001
May
71°FMay 29, 2009
49°FMay 8, 1948
Jun
81°FJun 30, 2015
52°FJun 7, 1950
Jul
80°FJul 20, 2003
67°FJul 10, 1974
Aug
77°FAug 2, 1971
61°FAug 7, 2009
Sep
70°FSep 2, 1949
53°FSep 30, 1971
Oct
62°FOct 2, 2015
37°FOct 29, 2009
Nov
53°FNov 21, 1974
13°FNov 18, 2014
Dec
50°FDec 22, 1955
-1°FDec 22, 1990
All-time
81°FJun 30, 2015
-1°FDec 22, 1990
Cold Streaks
Current run
0 days
consecutive days with a low ≤ 32°F
Longest ever
110 days
record run, ended Mar 20 1985
So far in 2026
73 days
days with a low ≤ 32°F this year
Climate Normals
Normal low & low by month, from Ontario's own 1991–2020 record. Today's normal low: 51°F · forecast is -6° vs normal.