Monthly outlook for Knollwood, IL: average high 80°, average low 67.4°. That is 1.3° above the climate normal for August. Precipitation is expected on 4 days (about 2.3 inches), against a normal of 6 days and 1.8 inches. The warmest day looks like 20 August (91.5°), the coolest 14 August (61.6°).
80°/67.4°
Average high / low
+1.3°
Above normal
4 / 6
Wet days / normal
2.3 in
Precipitation this month
Ten-day blocks vs climate normal
Period
Forecast high
Normal
Difference
9 August – 18 August
77.6°
77.9°
-0.2°
19 August – 28 August
84°
77.8°
+3.5°
29 August – 7 September
at normal
76.1°
—
August records over 66 years
98.6°24 August 2023All-time high
52.5°22 August 2024All-time low
Climate normals and records are computed from the nearest reference point — Highwood (6 mi).
Mon, 1088° / 71°0.41
88 °
Knollwood, Monday, 10 August
Rain. High 88°, low 71°.
Pressure29.88 inHg
Wind5.5 mph NE
Humidity73%
Visibility6.2 mi
Dew point71°
Tue, 1183° / 69°0.63
83 °
Knollwood, Tuesday, 11 August
Heavy rain. High 83°, low 69°.
Pressure29.83 inHg
Wind10.8 mph E
Humidity98%
Visibility6.2 mi
Dew point69°
Wed, 1281° / 69°0.03
81 °
Knollwood, Wednesday, 12 August
Light rain. High 81°, low 69°.
Pressure29.83 inHg
Wind3.2 mph NW
Humidity67%
Visibility6.2 mi
Dew point69°
Thu, 1372° / 65°0
72 °
Knollwood, Thursday, 13 August
Overcast. High 72°, low 65°.
Pressure30.03 inHg
Wind8.9 mph NE
Humidity56%
Visibility—
Dew point55°
Fri, 1472° / 62°0
72 °
Knollwood, Friday, 14 August
Partly cloudy. High 72°, low 62°.
Pressure30.18 inHg
Wind9.7 mph NE
Humidity52%
Visibility—
Dew point52°
Sat, 1575° / 63°0
75 °
Knollwood, Saturday, 15 August
Overcast. High 75°, low 63°.
Pressure30.24 inHg
Wind11.3 mph E
Humidity50%
Visibility—
Dew point53°
Sun, 1672° / 66°0.04
72 °
Knollwood, Sunday, 16 August
Light rain. High 72°, low 66°.
Pressure30.09 inHg
Wind8.2 mph SE
Humidity68%
Visibility—
Dew point59°
Mon, 1776° / 65°0.04
76 °
Knollwood, Monday, 17 August
Light rain. High 76°, low 65°.
Pressure30.09 inHg
Wind10.2 mph NE
Humidity69%
Visibility—
Dew point64°
Tue, 1876° / 65°0
76 °
Knollwood, Tuesday, 18 August
Overcast. High 76°, low 65°.
Pressure30.03 inHg
Wind5.3 mph SE
Humidity66%
Visibility—
Dew point59°
Wed, 1985° / 69°0.22
85 °
Knollwood, Wednesday, 19 August
Light rain. High 85°, low 69°.
Pressure29.88 inHg
Wind14.2 mph S
Humidity61%
Visibility—
Dew point65°
Thu, 2091° / 75°0
91 °
Knollwood, Thursday, 20 August
Overcast. High 91°, low 75°.
Pressure29.77 inHg
Wind6 mph S
Humidity63%
Visibility—
Dew point70°
Fri, 2180° / 70°0
80 °
Knollwood, Friday, 21 August
Clear. High 80°, low 70°.
Pressure29.94 inHg
Wind12.8 mph NE
Humidity60%
Visibility—
Dew point64°
Sat, 2288° / 69°0.02
88 °
Knollwood, Saturday, 22 August
Light rain. High 88°, low 69°.
Pressure29.88 inHg
Wind7.9 mph NE
Humidity54%
Visibility—
Dew point64°
Sun, 2385° / 69°0
85 °
Knollwood, Sunday, 23 August
Overcast. High 85°, low 69°.
Pressure29.83 inHg
Wind12.7 mph N
Humidity58%
Visibility—
Dew point68°
Mon, 2475° / 68°0.04
75 °
Knollwood, Monday, 24 August
Light rain. High 75°, low 68°.
Pressure30.06 inHg
Wind15.5 mph NE
Humidity80%
Visibility—
Dew point66°
From day 17 onward the outlook is built from 60-year climate statistics
Tue, 2578° / 68°0.07
78 °
Knollwood, Tuesday, 25 August
Climate normal for this date — 60-year average.
Average high78°
Average low68°
Average precipitation0.07 in
Chance of precipitation25%
Record high91° (2024)
Record low54° (2017)
Wed, 2679° / 68°0.14
79 °
Knollwood, Wednesday, 26 August
Climate normal for this date — 60-year average.
Average high79°
Average low68°
Average precipitation0.14 in
Chance of precipitation35%
Record high94° (2024)
Record low54° (2025)
Thu, 2778° / 69°0.1
78 °
Knollwood, Thursday, 27 August
Climate normal for this date — 60-year average.
Average high78°
Average low69°
Average precipitation0.1 in
Chance of precipitation32%
Record high96° (2024)
Record low55° (2025)
Fri, 2878° / 68°0.12
78 °
Knollwood, Friday, 28 August
Climate normal for this date — 60-year average.
Average high78°
Average low68°
Average precipitation0.12 in
Chance of precipitation35%
Record high92° (2021)
Record low54° (1986)
Sat, 2978° / 68°0.13
78 °
Knollwood, Saturday, 29 August
Climate normal for this date — 60-year average.
Average high78°
Average low68°
Average precipitation0.13 in
Chance of precipitation28%
Record high89° (1984)
Record low54° (1965)
Sun, 3077° / 67°0.09
77 °
Knollwood, Sunday, 30 August
Climate normal for this date — 60-year average.
Average high77°
Average low67°
Average precipitation0.09 in
Chance of precipitation27%
Record high91° (2013)
Record low57° (2023)
Mon, 3176° / 67°0.06
76 °
Knollwood, Monday, 31 August
Climate normal for this date — 60-year average.
Average high76°
Average low67°
Average precipitation0.06 in
Chance of precipitation20%
Record high89° (2012)
Record low56° (2025)
Tue, 0176° / 67°0.1
76 °
Knollwood, Tuesday, 1 September
Climate normal for this date — 60-year average.
Average high76°
Average low67°
Average precipitation0.1 in
Chance of precipitation28%
Record high89° (1960)
Record low57° (2017)
Wed, 0277° / 67°0.04
77 °
Knollwood, Wednesday, 2 September
Climate normal for this date — 60-year average.
Average high77°
Average low67°
Average precipitation0.04 in
Chance of precipitation25%
Record high87° (2023)
Record low50° (2017)
Thu, 0376° / 66°0.09
76 °
Knollwood, Thursday, 3 September
Climate normal for this date — 60-year average.
Average high76°
Average low66°
Average precipitation0.09 in
Chance of precipitation27%
Record high92° (2023)
Record low54° (1974)
Fri, 0475° / 66°0.08
75 °
Knollwood, Friday, 4 September
Climate normal for this date — 60-year average.
Average high75°
Average low66°
Average precipitation0.08 in
Chance of precipitation30%
Record high91° (2023)
Record low49° (2025)
Sat, 0575° / 65°0.08
75 °
Knollwood, Saturday, 5 September
Climate normal for this date — 60-year average.
Average high75°
Average low65°
Average precipitation0.08 in
Chance of precipitation25%
Record high89° (2023)
Record low55° (2017)
Sun, 0675° / 65°0.09
75 °
Knollwood, Sunday, 6 September
Climate normal for this date — 60-year average.
Average high75°
Average low65°
Average precipitation0.09 in
Chance of precipitation33%
Record high90° (1990)
Record low49° (2025)
Mon, 0775° / 65°0.07
75 °
Knollwood, Monday, 7 September
Climate normal for this date — 60-year average.
Average high75°
Average low65°
Average precipitation0.07 in
Chance of precipitation28%
Record high89° (1960)
Record low48° (2025)
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 Knollwood, 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 Knollwood, 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.