Monthly outlook for Deer Plain, IL: average high 74.9°, average low 54.4°. That is 5.1° above the climate normal for October. Precipitation is expected on 3 days (about 0.7 inches), against a normal of 5 days and 1.8 inches. The warmest day looks like 12 October (89.9°), the coolest 18 October (35.3°).
74.9°/54.4°
Average high / low
+5.1°
Above normal
3 / 5
Wet days / normal
0.7 in
Precipitation this month
Ten-day blocks vs climate normal
Period
Forecast high
Normal
Difference
11 October – 20 October
73.7°
66.8°
+3.8°
21 October – 30 October
76.9°
63.2°
+7.6°
31 October – 9 November
at normal
58.7°
—
October records over 66 years
91.9°10 October 1963All-time high
28.8°24 October 1981All-time low
Climate normals and records are computed from the nearest reference point — O'Fallon (14 mi).
Mon, 1290° / 62°0
90 °
Deer Plain, Monday, 12 October
Clear. High 90°, low 62°.
Pressure29.91 inHg
Wind9.7 mph SW
Humidity48%
Visibility6.2 mi
Dew point61°
Tue, 1389° / 69°0
89 °
Deer Plain, Tuesday, 13 October
Clear. High 89°, low 69°.
Pressure29.91 inHg
Wind8.6 mph SW
Humidity55%
Visibility6.2 mi
Dew point67°
Wed, 1478° / 70°0.21
78 °
Deer Plain, Wednesday, 14 October
Rain. High 78°, low 70°.
Pressure30.03 inHg
Wind6.1 mph SW
Humidity94%
Visibility2.2 mi
Dew point71°
Thu, 1576° / 69°0.28
76 °
Deer Plain, Thursday, 15 October
Rain. High 76°, low 69°.
Pressure30.03 inHg
Wind7.1 mph SW
Humidity94%
Visibility6.1 mi
Dew point73°
Fri, 1671° / 54°0.03
71 °
Deer Plain, Friday, 16 October
Light rain. High 71°, low 54°.
Pressure30.39 inHg
Wind15.9 mph N
Humidity45%
Visibility—
Dew point40°
Sat, 1750° / 36°0
50 °
Deer Plain, Saturday, 17 October
Clear. High 50°, low 36°.
Pressure30.59 inHg
Wind12.4 mph N
Humidity18%
Visibility—
Dew point5°
Sun, 1860° / 35°0
60 °
Deer Plain, Sunday, 18 October
Clear. High 60°, low 35°.
Pressure30.50 inHg
Wind13.6 mph S
Humidity18%
Visibility—
Dew point10°
Mon, 1969° / 40°0
69 °
Deer Plain, Monday, 19 October
Clear. High 69°, low 40°.
Pressure30.39 inHg
Wind12.5 mph SW
Humidity17%
Visibility—
Dew point17°
Tue, 2070° / 46°0
70 °
Deer Plain, Tuesday, 20 October
Overcast. High 70°, low 46°.
Pressure30.33 inHg
Wind10 mph S
Humidity22%
Visibility—
Dew point25°
Wed, 2175° / 52°0
75 °
Deer Plain, Wednesday, 21 October
Partly cloudy. High 75°, low 52°.
Pressure30.21 inHg
Wind10.5 mph S
Humidity21%
Visibility—
Dew point28°
Thu, 2278° / 57°0
78 °
Deer Plain, Thursday, 22 October
Clear. High 78°, low 57°.
Pressure30.21 inHg
Wind8.2 mph S
Humidity23%
Visibility—
Dew point33°
Fri, 2381° / 58°0
81 °
Deer Plain, Friday, 23 October
Clear. High 81°, low 58°.
Pressure30.15 inHg
Wind8.1 mph SW
Humidity30%
Visibility—
Dew point42°
Sat, 2482° / 60°0
82 °
Deer Plain, Saturday, 24 October
Clear. High 82°, low 60°.
Pressure30.12 inHg
Wind6 mph W
Humidity42%
Visibility—
Dew point52°
Sun, 2585° / 63°0.19
85 °
Deer Plain, Sunday, 25 October
Rain. High 85°, low 63°.
Pressure29.94 inHg
Wind18.2 mph W
Humidity41%
Visibility—
Dew point55°
Mon, 2660° / 47°0
60 °
Deer Plain, Monday, 26 October
Overcast. High 60°, low 47°.
Pressure29.97 inHg
Wind14.9 mph NW
Humidity39%
Visibility—
Dew point31°
From day 17 onward the outlook is built from 60-year climate statistics
Tue, 2762° / 46°0.09
62 °
Deer Plain, Tuesday, 27 October
Climate normal for this date — 60-year average.
Average high62°
Average low46°
Average precipitation0.09 in
Chance of precipitation20%
Record high80° (2023)
Record low33° (2001)
Wed, 2861° / 46°0.05
61 °
Deer Plain, Wednesday, 28 October
Climate normal for this date — 60-year average.
Average high61°
Average low46°
Average precipitation0.05 in
Chance of precipitation23%
Record high78° (1999)
Record low31° (1969)
Thu, 2962° / 46°0.13
62 °
Deer Plain, Thursday, 29 October
Climate normal for this date — 60-year average.
Average high62°
Average low46°
Average precipitation0.13 in
Chance of precipitation28%
Record high82° (2024)
Record low30° (2017)
Fri, 3063° / 47°0.12
63 °
Deer Plain, Friday, 30 October
Climate normal for this date — 60-year average.
Average high63°
Average low47°
Average precipitation0.12 in
Chance of precipitation30%
Record high82° (2024)
Record low29° (1980)
Sat, 3162° / 47°0.16
62 °
Deer Plain, Saturday, 31 October
Climate normal for this date — 60-year average.
Average high62°
Average low47°
Average precipitation0.16 in
Chance of precipitation42%
Record high80° (1968)
Record low29° (1993)
Sun, 0161° / 46°0.19
61 °
Deer Plain, Sunday, 1 November
Climate normal for this date — 60-year average.
Average high61°
Average low46°
Average precipitation0.19 in
Chance of precipitation28%
Record high80° (2016)
Record low26° (2023)
Mon, 0260° / 44°0.09
60 °
Deer Plain, Monday, 2 November
Climate normal for this date — 60-year average.
Average high60°
Average low44°
Average precipitation0.09 in
Chance of precipitation35%
Record high80° (2016)
Record low27° (1966)
Tue, 0358° / 43°0.12
58 °
Deer Plain, Tuesday, 3 November
Climate normal for this date — 60-year average.
Average high58°
Average low43°
Average precipitation0.12 in
Chance of precipitation30%
Record high78° (1987)
Record low19° (1991)
Wed, 0458° / 44°0.15
58 °
Deer Plain, Wednesday, 4 November
Climate normal for this date — 60-year average.
Average high58°
Average low44°
Average precipitation0.15 in
Chance of precipitation28%
Record high78° (1978)
Record low19° (1991)
Thu, 0557° / 43°0.17
57 °
Deer Plain, Thursday, 5 November
Climate normal for this date — 60-year average.
Average high57°
Average low43°
Average precipitation0.17 in
Chance of precipitation35%
Record high78° (1978)
Record low24° (1991)
Fri, 0657° / 42°0.09
57 °
Deer Plain, Friday, 6 November
Climate normal for this date — 60-year average.
Average high57°
Average low42°
Average precipitation0.09 in
Chance of precipitation32%
Record high77° (2023)
Record low28° (1982)
Sat, 0758° / 42°0.07
58 °
Deer Plain, Saturday, 7 November
Climate normal for this date — 60-year average.
Average high58°
Average low42°
Average precipitation0.07 in
Chance of precipitation13%
Record high74° (1980)
Record low15° (1991)
Sun, 0858° / 42°0.03
58 °
Deer Plain, Sunday, 8 November
Climate normal for this date — 60-year average.
Average high58°
Average low42°
Average precipitation0.03 in
Chance of precipitation17%
Record high82° (2023)
Record low0° (1991)
Mon, 0958° / 43°0.11
58 °
Deer Plain, Monday, 9 November
Climate normal for this date — 60-year average.
Average high58°
Average low43°
Average precipitation0.11 in
Chance of precipitation28%
Record high78° (2022)
Record low10° (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 Deer Plain, 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 Deer Plain, 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.