Monthly outlook for Summit, IL: average high 68.4°, average low 54.2°. That is 3.6° above the climate normal for October. Precipitation is expected on 1 day (about 0.1 inches), against a normal of 5 days and 1.7 inches. The warmest day looks like 15 October (90.2°), the coolest 18 October (46.3°).
68.4°/54.2°
Average high / low
+3.6°
Above normal
1 / 5
Wet days / normal
0.1 in
Precipitation this month
Ten-day blocks vs climate normal
Period
Forecast high
Normal
Difference
7 October – 16 October
73.5°
63.4°
+5.6°
17 October – 26 October
60°
58.8°
+0.6°
27 October – 5 November
at normal
55°
—
October records over 66 years
89.2°3 October 2025All-time high
25.7°26 October 1962All-time low
Thu, 0871° / 53°0
71 °
Summit, Thursday, 8 October
Clear. High 71°, low 53°.
Pressure30.09 inHg
Wind5.9 mph NW
Humidity49%
Visibility6.2 mi
Dew point46°
Fri, 0971° / 50°0.12
71 °
Summit, Friday, 9 October
Rain. High 71°, low 50°.
Pressure30.18 inHg
Wind6.2 mph SE
Humidity50%
Visibility6.2 mi
Dew point50°
Sat, 1079° / 59°0
79 °
Summit, Saturday, 10 October
Clear. High 79°, low 59°.
Pressure30.12 inHg
Wind7.2 mph S
Humidity56%
Visibility6.2 mi
Dew point57°
Sun, 1165° / 59°0
65 °
Summit, Sunday, 11 October
Overcast. High 65°, low 59°.
Pressure30.00 inHg
Wind4.5 mph E
Humidity76%
Visibility6.2 mi
Dew point56°
Mon, 1276° / 55°0
76 °
Summit, Monday, 12 October
Light rain. High 76°, low 55°.
Pressure29.85 inHg
Wind7.4 mph S
Humidity71%
Visibility—
Dew point60°
Tue, 1368° / 54°0.01
68 °
Summit, Tuesday, 13 October
Light rain. High 68°, low 54°.
Pressure30.00 inHg
Wind11.8 mph NE
Humidity53%
Visibility—
Dew point46°
Wed, 1469° / 53°0
69 °
Summit, Wednesday, 14 October
Overcast. High 69°, low 53°.
Pressure30.03 inHg
Wind10.6 mph SE
Humidity34%
Visibility—
Dew point34°
Thu, 1590° / 66°0
90 °
Summit, Thursday, 15 October
Partly cloudy. High 90°, low 66°.
Pressure29.74 inHg
Wind15.3 mph SW
Humidity47%
Visibility—
Dew point61°
Fri, 1667° / 56°0
67 °
Summit, Friday, 16 October
Clear. High 67°, low 56°.
Pressure30.24 inHg
Wind11.2 mph NW
Humidity37%
Visibility—
Dew point39°
Sat, 1756° / 49°0
56 °
Summit, Saturday, 17 October
Mostly clear. High 56°, low 49°.
Pressure30.30 inHg
Wind10.1 mph N
Humidity37%
Visibility—
Dew point29°
Sun, 1858° / 46°0
58 °
Summit, Sunday, 18 October
Clear. High 58°, low 46°.
Pressure30.39 inHg
Wind8.1 mph NE
Humidity28%
Visibility—
Dew point23°
Mon, 1961° / 47°0
61 °
Summit, Monday, 19 October
Overcast. High 61°, low 47°.
Pressure30.50 inHg
Wind9.3 mph S
Humidity31%
Visibility—
Dew point27°
Tue, 2059° / 53°0.01
59 °
Summit, Tuesday, 20 October
Light rain. High 59°, low 53°.
Pressure30.30 inHg
Wind8.3 mph SW
Humidity46%
Visibility—
Dew point35°
Wed, 2166° / 56°0
66 °
Summit, Wednesday, 21 October
Overcast. High 66°, low 56°.
Pressure30.09 inHg
Wind5.3 mph NE
Humidity46%
Visibility—
Dew point43°
Thu, 2261° / 55°0
61 °
Summit, Thursday, 22 October
Overcast. High 61°, low 55°.
Pressure29.80 inHg
Wind5.5 mph NE
Humidity44%
Visibility—
Dew point38°
From day 17 onward the outlook is built from 60-year climate statistics
Fri, 2359° / 46°0.13
59 °
Summit, Friday, 23 October
Climate normal for this date — 60-year average.
Average high59°
Average low46°
Average precipitation0.13 in
Chance of precipitation33%
Record high79° (1963)
Record low32° (1976)
Sat, 2458° / 46°0.12
58 °
Summit, Saturday, 24 October
Climate normal for this date — 60-year average.
Average high58°
Average low46°
Average precipitation0.12 in
Chance of precipitation38%
Record high79° (1963)
Record low26° (1981)
Sun, 2557° / 44°0.13
57 °
Summit, Sunday, 25 October
Climate normal for this date — 60-year average.
Average high57°
Average low44°
Average precipitation0.13 in
Chance of precipitation32%
Record high75° (1963)
Record low31° (1962)
Mon, 2656° / 44°0.11
56 °
Summit, Monday, 26 October
Climate normal for this date — 60-year average.
Average high56°
Average low44°
Average precipitation0.11 in
Chance of precipitation32%
Record high79° (1963)
Record low26° (1962)
Tue, 2756° / 44°0.1
56 °
Summit, Tuesday, 27 October
Climate normal for this date — 60-year average.
Average high56°
Average low44°
Average precipitation0.1 in
Chance of precipitation37%
Record high74° (2014)
Record low30° (1980)
Wed, 2856° / 43°0.06
56 °
Summit, Wednesday, 28 October
Climate normal for this date — 60-year average.
Average high56°
Average low43°
Average precipitation0.06 in
Chance of precipitation20%
Record high74° (1999)
Record low28° (1976)
Thu, 2956° / 43°0.06
56 °
Summit, Thursday, 29 October
Climate normal for this date — 60-year average.
Average high56°
Average low43°
Average precipitation0.06 in
Chance of precipitation20%
Record high79° (2024)
Record low29° (1980)
Fri, 3058° / 44°0.12
58 °
Summit, Friday, 30 October
Climate normal for this date — 60-year average.
Average high58°
Average low44°
Average precipitation0.12 in
Chance of precipitation28%
Record high78° (2024)
Record low28° (1988)
Sat, 3156° / 44°0.13
56 °
Summit, Saturday, 31 October
Climate normal for this date — 60-year average.
Average high56°
Average low44°
Average precipitation0.13 in
Chance of precipitation42%
Record high74° (1974)
Record low26° (2023)
Sun, 0155° / 43°0.18
55 °
Summit, Sunday, 1 November
Climate normal for this date — 60-year average.
Average high55°
Average low43°
Average precipitation0.18 in
Chance of precipitation42%
Record high73° (2016)
Record low19° (2019)
Mon, 0254° / 42°0.12
54 °
Summit, Monday, 2 November
Climate normal for this date — 60-year average.
Average high54°
Average low42°
Average precipitation0.12 in
Chance of precipitation40%
Record high74° (1961)
Record low24° (1991)
Tue, 0353° / 40°0.07
53 °
Summit, Tuesday, 3 November
Climate normal for this date — 60-year average.
Average high53°
Average low40°
Average precipitation0.07 in
Chance of precipitation27%
Record high72° (1987)
Record low19° (1991)
Wed, 0453° / 42°0.09
53 °
Summit, Wednesday, 4 November
Climate normal for this date — 60-year average.
Average high53°
Average low42°
Average precipitation0.09 in
Chance of precipitation28%
Record high71° (2015)
Record low18° (1991)
Thu, 0553° / 41°0.12
53 °
Summit, Thursday, 5 November
Climate normal for this date — 60-year average.
Average high53°
Average low41°
Average precipitation0.12 in
Chance of precipitation32%
Record high75° (1978)
Record low20° (1991)
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 Summit, IL 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 Summit, IL 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.