Monthly outlook for Harmony, IL: average high 66.1°, average low 49.1°. That is 2.8° above the climate normal for October. Precipitation is expected on 6 days (about 1.2 inches), against a normal of 5 days and 1.6 inches. The warmest day looks like 12 October (78.9°), the coolest 18 October (35.7°).
66.1°/49.1°
Average high / low
+2.8°
Above normal
6 / 5
Wet days / normal
1.2 in
Precipitation this month
Ten-day blocks vs climate normal
Period
Forecast high
Normal
Difference
8 October – 17 October
68.5°
62.3°
+3.5°
18 October – 27 October
62.2°
57.9°
+2.4°
28 October – 6 November
at normal
53.8°
—
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 (14 mi).
Fri, 0973° / 49°0.08
73 °
Harmony, Friday, 9 October
Light rain. High 73°, low 49°.
Pressure30.12 inHg
Wind9.4 mph SE
Humidity51%
Visibility6.2 mi
Dew point49°
Sat, 1075° / 57°0
75 °
Harmony, Saturday, 10 October
Overcast. High 75°, low 57°.
Pressure30.09 inHg
Wind9.9 mph S
Humidity57%
Visibility6.2 mi
Dew point55°
Sun, 1173° / 53°0
73 °
Harmony, Sunday, 11 October
Clear. High 73°, low 53°.
Pressure30.00 inHg
Wind2.6 mph SE
Humidity64%
Visibility6.2 mi
Dew point56°
Mon, 1279° / 58°0.13
79 °
Harmony, Monday, 12 October
Rain. High 79°, low 58°.
Pressure29.83 inHg
Wind11.3 mph SW
Humidity58%
Visibility6.2 mi
Dew point60°
Tue, 1366° / 52°0.48
66 °
Harmony, Tuesday, 13 October
Rain. High 66°, low 52°.
Pressure30.03 inHg
Wind11.8 mph NE
Humidity72%
Visibility—
Dew point50°
Wed, 1463° / 50°0.21
63 °
Harmony, Wednesday, 14 October
Light rain. High 63°, low 50°.
Pressure30.00 inHg
Wind14.2 mph SE
Humidity76%
Visibility—
Dew point47°
Thu, 1574° / 64°0.16
74 °
Harmony, Thursday, 15 October
Rain. High 74°, low 64°.
Pressure29.97 inHg
Wind15.3 mph S
Humidity48%
Visibility—
Dew point52°
Fri, 1664° / 47°0.01
64 °
Harmony, Friday, 16 October
Light rain. High 64°, low 47°.
Pressure30.30 inHg
Wind15.9 mph NW
Humidity53%
Visibility—
Dew point41°
Sat, 1749° / 38°0
49 °
Harmony, Saturday, 17 October
Clear. High 49°, low 38°.
Pressure30.50 inHg
Wind13.5 mph N
Humidity40%
Visibility—
Dew point24°
Sun, 1854° / 36°0
54 °
Harmony, Sunday, 18 October
Clear. High 54°, low 36°.
Pressure30.56 inHg
Wind5.5 mph NW
Humidity36%
Visibility—
Dew point24°
Mon, 1957° / 40°0
57 °
Harmony, Monday, 19 October
Clear. High 57°, low 40°.
Pressure30.45 inHg
Wind10.2 mph S
Humidity42%
Visibility—
Dew point31°
Tue, 2064° / 44°0
64 °
Harmony, Tuesday, 20 October
Mostly clear. High 64°, low 44°.
Pressure30.24 inHg
Wind11.9 mph S
Humidity50%
Visibility—
Dew point41°
Wed, 2166° / 52°0.14
66 °
Harmony, Wednesday, 21 October
Light rain. High 66°, low 52°.
Pressure30.03 inHg
Wind12.7 mph SW
Humidity68%
Visibility—
Dew point51°
Thu, 2266° / 48°0
66 °
Harmony, Thursday, 22 October
Clear. High 66°, low 48°.
Pressure30.15 inHg
Wind9 mph W
Humidity54%
Visibility—
Dew point45°
Fri, 2367° / 50°0
67 °
Harmony, Friday, 23 October
Clear. High 67°, low 50°.
Pressure30.21 inHg
Wind6.1 mph E
Humidity52%
Visibility—
Dew point46°
From day 17 onward the outlook is built from 60-year climate statistics
Sat, 2457° / 44°0.11
57 °
Harmony, Saturday, 24 October
Climate normal for this date — 60-year average.
Average high57°
Average low44°
Average precipitation0.11 in
Chance of precipitation38%
Record high78° (1963)
Record low22° (1981)
Sun, 2557° / 42°0.1
57 °
Harmony, Sunday, 25 October
Climate normal for this date — 60-year average.
Average high57°
Average low42°
Average precipitation0.1 in
Chance of precipitation27%
Record high75° (1989)
Record low27° (2006)
Mon, 2656° / 42°0.09
56 °
Harmony, Monday, 26 October
Climate normal for this date — 60-year average.
Average high56°
Average low42°
Average precipitation0.09 in
Chance of precipitation23%
Record high79° (1963)
Record low22° (1962)
Tue, 2756° / 41°0.08
56 °
Harmony, Tuesday, 27 October
Climate normal for this date — 60-year average.
Average high56°
Average low41°
Average precipitation0.08 in
Chance of precipitation22%
Record high75° (2014)
Record low27° (1997)
Wed, 2855° / 41°0.04
55 °
Harmony, Wednesday, 28 October
Climate normal for this date — 60-year average.
Average high55°
Average low41°
Average precipitation0.04 in
Chance of precipitation17%
Record high74° (1999)
Record low25° (1976)
Thu, 2955° / 40°0.06
55 °
Harmony, Thursday, 29 October
Climate normal for this date — 60-year average.
Average high55°
Average low40°
Average precipitation0.06 in
Chance of precipitation18%
Record high78° (2024)
Record low23° (1980)
Fri, 3057° / 41°0.1
57 °
Harmony, Friday, 30 October
Climate normal for this date — 60-year average.
Average high57°
Average low41°
Average precipitation0.1 in
Chance of precipitation27%
Record high77° (1971)
Record low22° (1988)
Sat, 3155° / 42°0.11
55 °
Harmony, Saturday, 31 October
Climate normal for this date — 60-year average.
Average high55°
Average low42°
Average precipitation0.11 in
Chance of precipitation42%
Record high73° (1974)
Record low26° (2019)
Sun, 0154° / 40°0.17
54 °
Harmony, Sunday, 1 November
Climate normal for this date — 60-year average.
Average high54°
Average low40°
Average precipitation0.17 in
Chance of precipitation38%
Record high73° (2000)
Record low18° (2019)
Mon, 0253° / 39°0.1
53 °
Harmony, 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 °
Harmony, 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 °
Harmony, 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 °
Harmony, 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 °
Harmony, 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)
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 Harmony, 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 Harmony, 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.