Monthly outlook for McLean, IL: average high 70.6°, average low 51.4°. That is 3.9° above the climate normal for October. Precipitation is expected on 2 days (about 0.3 inches), against a normal of 5 days and 1.6 inches. The warmest day looks like 12 October (86°), the coolest 18 October (32.9°).
70.6°/51.4°
Average high / low
+3.9°
Above normal
2 / 5
Wet days / normal
0.3 in
Precipitation this month
Ten-day blocks vs climate normal
Period
Forecast high
Normal
Difference
9 October – 18 October
71.7°
64.7°
+3.9°
19 October – 28 October
68.6°
60.3°
+4.6°
29 October – 7 November
at normal
56.4°
—
October records over 66 years
89.1°7 October 2007All-time high
19.6°22 October 1976All-time low
Climate normals and records are computed from the nearest reference point — Shirley (9 mi).
Sat, 1078° / 57°0
78 °
McLean, Saturday, 10 October
Overcast. High 78°, low 57°.
Pressure30.06 inHg
Wind7.6 mph SE
Humidity49%
Visibility6.2 mi
Dew point54°
Sun, 1178° / 54°0
78 °
McLean, Sunday, 11 October
Clear. High 78°, low 54°.
Pressure29.94 inHg
Wind1 mph NE
Humidity59%
Visibility6.2 mi
Dew point58°
Mon, 1286° / 64°0
86 °
McLean, Monday, 12 October
Mostly clear. High 86°, low 64°.
Pressure29.85 inHg
Wind11.5 mph SW
Humidity47%
Visibility6.2 mi
Dew point60°
Tue, 1386° / 71°0
86 °
McLean, Tuesday, 13 October
Mostly clear. High 86°, low 71°.
Pressure29.83 inHg
Wind10.1 mph W
Humidity59%
Visibility6.2 mi
Dew point68°
Wed, 1470° / 61°0.1
70 °
McLean, Wednesday, 14 October
Light rain. High 70°, low 61°.
Pressure30.06 inHg
Wind13.1 mph NE
Humidity75%
Visibility—
Dew point60°
Thu, 1578° / 57°0.22
78 °
McLean, Thursday, 15 October
Light rain. High 78°, low 57°.
Pressure29.91 inHg
Wind19.8 mph SW
Humidity82%
Visibility—
Dew point60°
Fri, 1665° / 49°0.01
65 °
McLean, Friday, 16 October
Light rain. High 65°, low 49°.
Pressure30.06 inHg
Wind21 mph W
Humidity39%
Visibility—
Dew point32°
Sat, 1745° / 38°0
45 °
McLean, Saturday, 17 October
Overcast. High 45°, low 38°.
Pressure30.36 inHg
Wind21 mph W
Humidity51%
Visibility—
Dew point27°
Sun, 1851° / 33°0
51 °
McLean, Sunday, 18 October
Clear. High 51°, low 33°.
Pressure30.50 inHg
Wind6.1 mph N
Humidity37%
Visibility—
Dew point22°
Mon, 1957° / 40°0
57 °
McLean, Monday, 19 October
Overcast. High 57°, low 40°.
Pressure30.42 inHg
Wind9.5 mph S
Humidity37%
Visibility—
Dew point27°
Tue, 2064° / 43°0
64 °
McLean, Tuesday, 20 October
Clear. High 64°, low 43°.
Pressure30.39 inHg
Wind7.4 mph SE
Humidity29%
Visibility—
Dew point27°
Wed, 2169° / 46°0
69 °
McLean, Wednesday, 21 October
Clear. High 69°, low 46°.
Pressure30.30 inHg
Wind10.3 mph S
Humidity29%
Visibility—
Dew point31°
Thu, 2272° / 49°0
72 °
McLean, Thursday, 22 October
Clear. High 72°, low 49°.
Pressure30.12 inHg
Wind10.7 mph W
Humidity36%
Visibility—
Dew point39°
Fri, 2374° / 52°0
74 °
McLean, Friday, 23 October
Clear. High 74°, low 52°.
Pressure30.03 inHg
Wind7.3 mph SW
Humidity38%
Visibility—
Dew point42°
Sat, 2476° / 54°0
76 °
McLean, Saturday, 24 October
Clear. High 76°, low 54°.
Pressure30.03 inHg
Wind13.2 mph SW
Humidity28%
Visibility—
Dew point37°
From day 17 onward the outlook is built from 60-year climate statistics
Sun, 2560° / 44°0.14
60 °
McLean, Sunday, 25 October
Climate normal for this date — 60-year average.
Average high60°
Average low44°
Average precipitation0.14 in
Chance of precipitation23%
Record high77° (1963)
Record low28° (2013)
Mon, 2658° / 44°0.14
58 °
McLean, Monday, 26 October
Climate normal for this date — 60-year average.
Average high58°
Average low44°
Average precipitation0.14 in
Chance of precipitation30%
Record high81° (1963)
Record low22° (1962)
Tue, 2759° / 43°0.09
59 °
McLean, Tuesday, 27 October
Climate normal for this date — 60-year average.
Average high59°
Average low43°
Average precipitation0.09 in
Chance of precipitation28%
Record high76° (1984)
Record low30° (1997)
Wed, 2858° / 42°0.06
58 °
McLean, Wednesday, 28 October
Climate normal for this date — 60-year average.
Average high58°
Average low42°
Average precipitation0.06 in
Chance of precipitation23%
Record high75° (1999)
Record low25° (1976)
Thu, 2958° / 42°0.08
58 °
McLean, Thursday, 29 October
Climate normal for this date — 60-year average.
Average high58°
Average low42°
Average precipitation0.08 in
Chance of precipitation25%
Record high78° (2024)
Record low24° (1980)
Fri, 3060° / 44°0.11
60 °
McLean, Friday, 30 October
Climate normal for this date — 60-year average.
Average high60°
Average low44°
Average precipitation0.11 in
Chance of precipitation27%
Record high80° (1971)
Record low25° (1980)
Sat, 3159° / 44°0.17
59 °
McLean, Saturday, 31 October
Climate normal for this date — 60-year average.
Average high59°
Average low44°
Average precipitation0.17 in
Chance of precipitation42%
Record high76° (1968)
Record low27° (2019)
Sun, 0158° / 43°0.19
58 °
McLean, Sunday, 1 November
Climate normal for this date — 60-year average.
Average high58°
Average low43°
Average precipitation0.19 in
Chance of precipitation37%
Record high78° (2016)
Record low24° (2023)
Mon, 0256° / 41°0.08
56 °
McLean, Monday, 2 November
Climate normal for this date — 60-year average.
Average high56°
Average low41°
Average precipitation0.08 in
Chance of precipitation35%
Record high76° (1961)
Record low24° (1996)
Tue, 0355° / 40°0.09
55 °
McLean, Tuesday, 3 November
Climate normal for this date — 60-year average.
Average high55°
Average low40°
Average precipitation0.09 in
Chance of precipitation28%
Record high76° (1987)
Record low17° (1991)
Wed, 0455° / 42°0.09
55 °
McLean, Wednesday, 4 November
Climate normal for this date — 60-year average.
Average high55°
Average low42°
Average precipitation0.09 in
Chance of precipitation28%
Record high76° (1978)
Record low16° (1991)
Thu, 0555° / 40°0.13
55 °
McLean, Thursday, 5 November
Climate normal for this date — 60-year average.
Average high55°
Average low40°
Average precipitation0.13 in
Chance of precipitation27%
Record high77° (1978)
Record low18° (1991)
Fri, 0655° / 39°0.08
55 °
McLean, Friday, 6 November
Climate normal for this date — 60-year average.
Average high55°
Average low39°
Average precipitation0.08 in
Chance of precipitation28%
Record high71° (2020)
Record low26° (1991)
Sat, 0754° / 39°0.06
54 °
McLean, Saturday, 7 November
Climate normal for this date — 60-year average.
Average high54°
Average low39°
Average precipitation0.06 in
Chance of precipitation20%
Record high70° (1966)
Record low17° (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 McLean, 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 McLean, 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.