Monthly outlook for Ontario, CA: average high 76.8°, average low 62.7°. That is 0.6° above the climate normal for October. Precipitation is expected on 2 days (about 1.3 inches), against a normal of 2 days and 0.5 inches. The warmest day looks like 28 October (86.6°), the coolest 23 October (51.5°).
76.8°/62.7°
Average high / low
+0.6°
Above normal
2 / 2
Wet days / normal
1.3 in
Precipitation this month
Ten-day blocks vs climate normal
Period
Forecast high
Normal
Difference
21 October – 30 October
75.2°
76.4°
-0.6°
31 October – 9 November
79.5°
73.6°
+3.3°
10 November – 19 November
at normal
70.1°
—
October records over 66 years
105.4°1 October 2020All-time high
31.5°30 October 1971All-time low
Thu, 2264° / 55°0.63
64 °
Ontario, Thursday, 22 October
Rain. High 64°, low 55°.
Pressure30.00 inHg
Wind3.2 mph SW
Humidity75%
Visibility4.4 mi
Dew point53°
Fri, 2365° / 52°0
65 °
Ontario, Friday, 23 October
Partly cloudy. High 65°, low 52°.
Pressure30.00 inHg
Wind0.6 mph W
Humidity68%
Visibility6.2 mi
Dew point51°
Sat, 2469° / 53°0
69 °
Ontario, Saturday, 24 October
Clear. High 69°, low 53°.
Pressure29.97 inHg
Wind2.7 mph SW
Humidity68%
Visibility6.2 mi
Dew point57°
Sun, 2574° / 57°0
74 °
Ontario, Sunday, 25 October
Clear. High 74°, low 57°.
Pressure30.03 inHg
Wind0.8 mph SW
Humidity56%
Visibility6.2 mi
Dew point53°
Mon, 2676° / 56°0
76 °
Ontario, Monday, 26 October
Clear. High 76°, low 56°.
Pressure30.09 inHg
Wind3.4 mph W
Humidity52%
Visibility—
Dew point51°
Tue, 2783° / 58°0
83 °
Ontario, Tuesday, 27 October
Partly cloudy. High 83°, low 58°.
Pressure30.06 inHg
Wind5.8 mph W
Humidity40%
Visibility—
Dew point47°
Wed, 2887° / 74°0
87 °
Ontario, Wednesday, 28 October
Overcast. High 87°, low 74°.
Pressure29.97 inHg
Wind5.3 mph SW
Humidity18%
Visibility—
Dew point33°
Thu, 2983° / 73°0
83 °
Ontario, Thursday, 29 October
Overcast. High 83°, low 73°.
Pressure29.88 inHg
Wind8.9 mph SW
Humidity17%
Visibility—
Dew point31°
Fri, 3077° / 67°0
77 °
Ontario, Friday, 30 October
Overcast. High 77°, low 67°.
Pressure29.83 inHg
Wind10.6 mph W
Humidity46%
Visibility—
Dew point50°
Sat, 3170° / 63°0
70 °
Ontario, Saturday, 31 October
Overcast. High 70°, low 63°.
Pressure29.85 inHg
Wind9.1 mph SW
Humidity63%
Visibility—
Dew point53°
Sun, 0176° / 62°0
76 °
Ontario, Sunday, 1 November
Clear. High 76°, low 62°.
Pressure30.06 inHg
Wind8.3 mph W
Humidity51%
Visibility—
Dew point49°
Mon, 0283° / 67°0
83 °
Ontario, Monday, 2 November
Clear. High 83°, low 67°.
Pressure30.09 inHg
Wind8.7 mph W
Humidity28%
Visibility—
Dew point40°
Tue, 0383° / 70°0
83 °
Ontario, Tuesday, 3 November
Clear. High 83°, low 70°.
Pressure30.09 inHg
Wind8.5 mph SW
Humidity23%
Visibility—
Dew point36°
Wed, 0482° / 69°0
82 °
Ontario, Wednesday, 4 November
Clear. High 82°, low 69°.
Pressure30.03 inHg
Wind8 mph W
Humidity29%
Visibility—
Dew point41°
Thu, 0584° / 68°0
84 °
Ontario, Thursday, 5 November
Clear. High 84°, low 68°.
Pressure30.06 inHg
Wind7.2 mph W
Humidity33%
Visibility—
Dew point44°
From day 17 onward the outlook is built from 60-year climate statistics
Fri, 0673° / 51°0.02
73 °
Ontario, Friday, 6 November
Climate normal for this date — 60-year average.
Average high73°
Average low51°
Average precipitation0.02 in
Chance of precipitation10%
Record high89° (2006)
Record low41° (2011)
Sat, 0772° / 50°0.06
72 °
Ontario, Saturday, 7 November
Climate normal for this date — 60-year average.
Average high72°
Average low50°
Average precipitation0.06 in
Chance of precipitation10%
Record high91° (2006)
Record low35° (2011)
Sun, 0871° / 50°0.08
71 °
Ontario, Sunday, 8 November
Climate normal for this date — 60-year average.
Average high71°
Average low50°
Average precipitation0.08 in
Chance of precipitation23%
Record high90° (2016)
Record low36° (2011)
Mon, 0971° / 49°0.06
71 °
Ontario, Monday, 9 November
Climate normal for this date — 60-year average.
Average high71°
Average low49°
Average precipitation0.06 in
Chance of precipitation17%
Record high91° (2025)
Record low38° (2011)
Tue, 1071° / 49°0.04
71 °
Ontario, Tuesday, 10 November
Climate normal for this date — 60-year average.
Average high71°
Average low49°
Average precipitation0.04 in
Chance of precipitation15%
Record high92° (2025)
Record low39° (1998)
Wed, 1171° / 48°0.07
71 °
Ontario, Wednesday, 11 November
Climate normal for this date — 60-year average.
Average high71°
Average low48°
Average precipitation0.07 in
Chance of precipitation15%
Record high89° (2021)
Record low37° (2012)
Thu, 1271° / 48°0.04
71 °
Ontario, Thursday, 12 November
Climate normal for this date — 60-year average.
Average high71°
Average low48°
Average precipitation0.04 in
Chance of precipitation13%
Record high91° (2021)
Record low33° (2000)
Fri, 1371° / 47°0.04
71 °
Ontario, Friday, 13 November
Climate normal for this date — 60-year average.
Average high71°
Average low47°
Average precipitation0.04 in
Chance of precipitation13%
Record high92° (2021)
Record low32° (1985)
Sat, 1471° / 48°0.05
71 °
Ontario, Saturday, 14 November
Climate normal for this date — 60-year average.
Average high71°
Average low48°
Average precipitation0.05 in
Chance of precipitation17%
Record high91° (2021)
Record low34° (1964)
Sun, 1570° / 47°0.06
70 °
Ontario, Sunday, 15 November
Climate normal for this date — 60-year average.
Average high70°
Average low47°
Average precipitation0.06 in
Chance of precipitation12%
Record high88° (2021)
Record low33° (1964)
Mon, 1669° / 48°0.06
69 °
Ontario, Monday, 16 November
Climate normal for this date — 60-year average.
Average high69°
Average low48°
Average precipitation0.06 in
Chance of precipitation17%
Record high88° (2020)
Record low33° (1964)
Tue, 1769° / 48°0.04
69 °
Ontario, Tuesday, 17 November
Climate normal for this date — 60-year average.
Average high69°
Average low48°
Average precipitation0.04 in
Chance of precipitation15%
Record high90° (2019)
Record low35° (1971)
Wed, 1869° / 47°0.08
69 °
Ontario, Wednesday, 18 November
Climate normal for this date — 60-year average.
Average high69°
Average low47°
Average precipitation0.08 in
Chance of precipitation22%
Record high88° (2019)
Record low32° (1964)
Thu, 1969° / 46°0.06
69 °
Ontario, Thursday, 19 November
Climate normal for this date — 60-year average.
Average high69°
Average low46°
Average precipitation0.06 in
Chance of precipitation8%
Record high86° (2006)
Record low29° (1964)
About the monthly outlook
How accurate is a 30-day forecast?
The first 16 days come from weather models — reliable for the first 3–5 days and progressively less so after that. Days 17 through 30 for Ontario, CA are built from the climate normal, the 60-year average, so they show typical weather for those dates rather than a specific forecast.
What does "above normal" mean?
We compare the forecast against the climate normal for those exact calendar days, computed from 60 years of observations. The deviation shows how much the coming month differs from a typical one.
Where do the 66-year records come from?
They are real temperature extremes recorded in Ontario, CA since 1960: the highest and lowest reading for each calendar date, with the year it happened.
How often is it updated?
The forecast portion refreshes every hour; the climate portion is based on long-term data and stays stable.