Monthly outlook for DeKalb, IL: average high 62.3°, average low 46°. That is 2.9° above the climate normal for October. Precipitation is expected on 2 days (about 0.2 inches), against a normal of 5 days and 1.5 inches. The warmest day looks like 24 October (68.1°), the coolest 17 October (34.7°).
62.3°/46°
Average high / low
+2.9°
Above normal
2 / 5
Wet days / normal
0.2 in
Precipitation this month
Ten-day blocks vs climate normal
Period
Forecast high
Normal
Difference
17 October – 26 October
62.9°
58.3°
+2.6°
27 October – 5 November
61.4°
54.2°
+4°
6 November – 15 November
at normal
48.5°
—
October records over 66 years
87.1°3 October 2025All-time high
22.1°24 October 1981All-time low
Climate normals and records are computed from the nearest reference point — Sycamore (6 mi).
Sun, 1863° / 43°0
63 °
DeKalb, Sunday, 18 October
Clear. High 63°, low 43°.
Pressure30.42 inHg
Wind13.9 mph SW
Humidity48%
Visibility6.2 mi
Dew point37°
Mon, 1964° / 42°0
64 °
DeKalb, Monday, 19 October
Partly cloudy. High 64°, low 42°.
Pressure30.39 inHg
Wind3.3 mph SW
Humidity54%
Visibility6.2 mi
Dew point44°
Tue, 2065° / 43°0
65 °
DeKalb, Tuesday, 20 October
Clear. High 65°, low 43°.
Pressure30.39 inHg
Wind4.4 mph SE
Humidity54%
Visibility6.2 mi
Dew point46°
Wed, 2167° / 45°0
67 °
DeKalb, Wednesday, 21 October
Clear. High 67°, low 45°.
Pressure30.27 inHg
Wind4 mph S
Humidity54%
Visibility6.2 mi
Dew point46°
Thu, 2268° / 48°0
68 °
DeKalb, Thursday, 22 October
Overcast. High 68°, low 48°.
Pressure30.27 inHg
Wind6.8 mph NE
Humidity53%
Visibility—
Dew point47°
Fri, 2367° / 51°0
67 °
DeKalb, Friday, 23 October
Partly cloudy. High 67°, low 51°.
Pressure30.33 inHg
Wind10.5 mph SE
Humidity56%
Visibility—
Dew point47°
Sat, 2468° / 54°0
68 °
DeKalb, Saturday, 24 October
Overcast. High 68°, low 54°.
Pressure30.18 inHg
Wind15.7 mph S
Humidity41%
Visibility—
Dew point41°
Sun, 2558° / 42°0
58 °
DeKalb, Sunday, 25 October
Overcast. High 58°, low 42°.
Pressure30.42 inHg
Wind14.1 mph NW
Humidity63%
Visibility—
Dew point35°
Mon, 2653° / 36°0
53 °
DeKalb, Monday, 26 October
Clear. High 53°, low 36°.
Pressure30.42 inHg
Wind7.7 mph W
Humidity40%
Visibility—
Dew point26°
Tue, 2756° / 39°0
56 °
DeKalb, Tuesday, 27 October
Overcast. High 56°, low 39°.
Pressure30.30 inHg
Wind9.9 mph S
Humidity37%
Visibility—
Dew point27°
Wed, 2859° / 48°0.01
59 °
DeKalb, Wednesday, 28 October
Light rain. High 59°, low 48°.
Pressure30.06 inHg
Wind17.9 mph S
Humidity73%
Visibility—
Dew point48°
Thu, 2964° / 57°0.04
64 °
DeKalb, Thursday, 29 October
Light rain. High 64°, low 57°.
Pressure29.80 inHg
Wind21.3 mph S
Humidity75%
Visibility—
Dew point49°
Fri, 3064° / 52°0.01
64 °
DeKalb, Friday, 30 October
Light rain. High 64°, low 52°.
Pressure29.94 inHg
Wind10.3 mph NW
Humidity26%
Visibility—
Dew point26°
Sat, 3164° / 49°0.13
64 °
DeKalb, Saturday, 31 October
Light rain. High 64°, low 49°.
Pressure30.03 inHg
Wind15.2 mph SE
Humidity57%
Visibility—
Dew point46°
Sun, 0162° / 50°0.01
62 °
DeKalb, Sunday, 1 November
Light rain. High 62°, low 50°.
Pressure29.83 inHg
Wind21 mph W
Humidity51%
Visibility—
Dew point43°
From day 17 onward the outlook is built from 60-year climate statistics
Mon, 0253° / 39°0.1
53 °
DeKalb, Monday, 2 November
Climate normal for this date — 60-year average.
Average high53°
Average low39°
Average precipitation0.1 in
Chance of precipitation33%
Record high74° (1961)
Record low21° (1991)
Tue, 0352° / 38°0.07
52 °
DeKalb, Tuesday, 3 November
Climate normal for this date — 60-year average.
Average high52°
Average low38°
Average precipitation0.07 in
Chance of precipitation28%
Record high72° (1964)
Record low16° (1991)
Wed, 0452° / 40°0.1
52 °
DeKalb, Wednesday, 4 November
Climate normal for this date — 60-year average.
Average high52°
Average low40°
Average precipitation0.1 in
Chance of precipitation25%
Record high71° (2015)
Record low14° (1991)
Thu, 0552° / 38°0.11
52 °
DeKalb, Thursday, 5 November
Climate normal for this date — 60-year average.
Average high52°
Average low38°
Average precipitation0.11 in
Chance of precipitation27%
Record high73° (1978)
Record low17° (1991)
Fri, 0651° / 37°0.09
51 °
DeKalb, Friday, 6 November
Climate normal for this date — 60-year average.
Average high51°
Average low37°
Average precipitation0.09 in
Chance of precipitation27%
Record high71° (1975)
Record low22° (1991)
Sat, 0751° / 37°0.03
51 °
DeKalb, Saturday, 7 November
Climate normal for this date — 60-year average.
Average high51°
Average low37°
Average precipitation0.03 in
Chance of precipitation20%
Record high67° (2009)
Record low13° (1991)
Sun, 0851° / 37°0.05
51 °
DeKalb, Sunday, 8 November
Climate normal for this date — 60-year average.
Average high51°
Average low37°
Average precipitation0.05 in
Chance of precipitation13%
Record high72° (2020)
Record low12° (1991)
Mon, 0951° / 37°0.12
51 °
DeKalb, Monday, 9 November
Climate normal for this date — 60-year average.
Average high51°
Average low37°
Average precipitation0.12 in
Chance of precipitation33%
Record high73° (1999)
Record low17° (1991)
Tue, 1049° / 35°0.1
49 °
DeKalb, Tuesday, 10 November
Climate normal for this date — 60-year average.
Average high49°
Average low35°
Average precipitation0.1 in
Chance of precipitation33%
Record high72° (2022)
Record low15° (2017)
Wed, 1147° / 33°0.07
47 °
DeKalb, Wednesday, 11 November
Climate normal for this date — 60-year average.
Average high47°
Average low33°
Average precipitation0.07 in
Chance of precipitation25%
Record high70° (1964)
Record low13° (2019)
Thu, 1246° / 32°0.06
46 °
DeKalb, Thursday, 12 November
Climate normal for this date — 60-year average.
Average high46°
Average low32°
Average precipitation0.06 in
Chance of precipitation23%
Record high65° (1964)
Record low1° (2019)
Fri, 1346° / 32°0.04
46 °
DeKalb, Friday, 13 November
Climate normal for this date — 60-year average.
Average high46°
Average low32°
Average precipitation0.04 in
Chance of precipitation20%
Record high70° (1999)
Record low1° (2019)
Sat, 1447° / 32°0.07
47 °
DeKalb, Saturday, 14 November
Climate normal for this date — 60-year average.
Average high47°
Average low32°
Average precipitation0.07 in
Chance of precipitation30%
Record high69° (1971)
Record low13° (1986)
Sun, 1546° / 33°0.08
46 °
DeKalb, Sunday, 15 November
Climate normal for this date — 60-year average.
Average high46°
Average low33°
Average precipitation0.08 in
Chance of precipitation23%
Record high69° (2025)
Record low14° (2019)
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 DeKalb, 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 DeKalb, 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.