Monthly outlook for Allegan, MI: average high 78.6°, average low 58.7°. That is 0.9° above the climate normal for August. Precipitation is expected on 3 days (about 2.6 inches), against a normal of 6 days and 2.2 inches. The warmest day looks like 9 August (84.6°), the coolest 21 August (49.5°).
78.6°/58.7°
Average high / low
+0.9°
Above normal
3 / 6
Wet days / normal
2.6 in
Precipitation this month
Ten-day blocks vs climate normal
Period
Forecast high
Normal
Difference
9 August – 18 August
79.8°
77.3°
+1.4°
19 August – 28 August
76.6°
77°
-0.2°
29 August – 7 September
at normal
75.3°
—
August records over 66 years
90.5°4 August 2012All-time high
47.7°29 August 2025All-time low
Climate normals and records are computed from the nearest reference point — Fennville (14 mi).
Mon, 1085° / 69°0.33
85 °
Allegan, Monday, 10 August
Rain. High 85°, low 69°.
Pressure29.94 inHg
Wind2.5 mph SW
Humidity77%
Visibility6.2 mi
Dew point70°
Tue, 1178° / 66°1.34
78 °
Allegan, Tuesday, 11 August
Heavy rain. High 78°, low 66°.
Pressure29.77 inHg
Wind10.2 mph W
Humidity97%
Visibility0.8 mi
Dew point66°
Wed, 1281° / 63°0
81 °
Allegan, Wednesday, 12 August
Overcast. High 81°, low 63°.
Pressure29.83 inHg
Wind5.2 mph NW
Humidity64%
Visibility6.2 mi
Dew point65°
Thu, 1372° / 55°0
72 °
Allegan, Thursday, 13 August
Overcast. High 72°, low 55°.
Pressure30.03 inHg
Wind9 mph NW
Humidity46%
Visibility—
Dew point48°
Fri, 1477° / 53°0
77 °
Allegan, Friday, 14 August
Clear. High 77°, low 53°.
Pressure30.09 inHg
Wind11.7 mph NW
Humidity45%
Visibility—
Dew point51°
Sat, 1579° / 55°0
79 °
Allegan, Saturday, 15 August
Overcast. High 79°, low 55°.
Pressure30.27 inHg
Wind6.4 mph NW
Humidity41%
Visibility—
Dew point50°
Sun, 1679° / 57°0
79 °
Allegan, Sunday, 16 August
Partly cloudy. High 79°, low 57°.
Pressure30.12 inHg
Wind6.2 mph S
Humidity46%
Visibility—
Dew point54°
Mon, 1779° / 62°0
79 °
Allegan, Monday, 17 August
Partly cloudy. High 79°, low 62°.
Pressure30.03 inHg
Wind9.2 mph W
Humidity55%
Visibility—
Dew point59°
Tue, 1884° / 61°0
84 °
Allegan, Tuesday, 18 August
Overcast. High 84°, low 61°.
Pressure29.97 inHg
Wind11.6 mph SW
Humidity48%
Visibility—
Dew point60°
Wed, 1975° / 63°0.02
75 °
Allegan, Wednesday, 19 August
Light rain. High 75°, low 63°.
Pressure29.85 inHg
Wind18.5 mph NW
Humidity74%
Visibility—
Dew point61°
Thu, 2074° / 56°0
74 °
Allegan, Thursday, 20 August
Overcast. High 74°, low 56°.
Pressure29.97 inHg
Wind14.1 mph NW
Humidity44%
Visibility—
Dew point49°
Fri, 2178° / 49°0
78 °
Allegan, Friday, 21 August
Clear. High 78°, low 49°.
Pressure30.06 inHg
Wind7.9 mph W
Humidity32%
Visibility—
Dew point41°
Sat, 2270° / 51°0
70 °
Allegan, Saturday, 22 August
Light rain. High 70°, low 51°.
Pressure29.97 inHg
Wind14.2 mph SE
Humidity57%
Visibility—
Dew point50°
Sun, 2380° / 63°0.01
80 °
Allegan, Sunday, 23 August
Light rain. High 80°, low 63°.
Pressure29.85 inHg
Wind18.8 mph W
Humidity40%
Visibility—
Dew point52°
Mon, 2483° / 58°0
83 °
Allegan, Monday, 24 August
Overcast. High 83°, low 58°.
Pressure30.00 inHg
Wind6.5 mph NW
Humidity34%
Visibility—
Dew point49°
From day 17 onward the outlook is built from 60-year climate statistics
Tue, 2577° / 66°0.1
77 °
Allegan, Tuesday, 25 August
Climate normal for this date — 60-year average.
Average high77°
Average low66°
Average precipitation0.1 in
Chance of precipitation30%
Record high86° (2012)
Record low52° (2017)
Wed, 2678° / 66°0.1
78 °
Allegan, Wednesday, 26 August
Climate normal for this date — 60-year average.
Average high78°
Average low66°
Average precipitation0.1 in
Chance of precipitation32%
Record high89° (2024)
Record low54° (2017)
Thu, 2777° / 66°0.15
77 °
Allegan, Thursday, 27 August
Climate normal for this date — 60-year average.
Average high77°
Average low66°
Average precipitation0.15 in
Chance of precipitation43%
Record high88° (2024)
Record low52° (2025)
Fri, 2877° / 66°0.19
77 °
Allegan, Friday, 28 August
Climate normal for this date — 60-year average.
Average high77°
Average low66°
Average precipitation0.19 in
Chance of precipitation40%
Record high87° (2021)
Record low51° (1986)
Sat, 2976° / 65°0.14
76 °
Allegan, Saturday, 29 August
Climate normal for this date — 60-year average.
Average high76°
Average low65°
Average precipitation0.14 in
Chance of precipitation40%
Record high87° (1984)
Record low48° (2025)
Sun, 3076° / 65°0.07
76 °
Allegan, Sunday, 30 August
Climate normal for this date — 60-year average.
Average high76°
Average low65°
Average precipitation0.07 in
Chance of precipitation23%
Record high86° (2010)
Record low48° (2025)
Mon, 3176° / 64°0.09
76 °
Allegan, Monday, 31 August
Climate normal for this date — 60-year average.
Average high76°
Average low64°
Average precipitation0.09 in
Chance of precipitation18%
Record high86° (2010)
Record low50° (2025)
Tue, 0176° / 64°0.13
76 °
Allegan, Tuesday, 1 September
Climate normal for this date — 60-year average.
Average high76°
Average low64°
Average precipitation0.13 in
Chance of precipitation30%
Record high88° (2011)
Record low51° (2017)
Wed, 0276° / 64°0.09
76 °
Allegan, Wednesday, 2 September
Climate normal for this date — 60-year average.
Average high76°
Average low64°
Average precipitation0.09 in
Chance of precipitation27%
Record high87° (2008)
Record low48° (2017)
Thu, 0376° / 64°0.08
76 °
Allegan, Thursday, 3 September
Climate normal for this date — 60-year average.
Average high76°
Average low64°
Average precipitation0.08 in
Chance of precipitation27%
Record high87° (1973)
Record low50° (1974)
Fri, 0474° / 63°0.07
74 °
Allegan, Friday, 4 September
Climate normal for this date — 60-year average.
Average high74°
Average low63°
Average precipitation0.07 in
Chance of precipitation30%
Record high87° (1999)
Record low51° (2025)
Sat, 0575° / 63°0.08
75 °
Allegan, Saturday, 5 September
Climate normal for this date — 60-year average.
Average high75°
Average low63°
Average precipitation0.08 in
Chance of precipitation23%
Record high88° (2023)
Record low52° (2019)
Sun, 0674° / 63°0.11
74 °
Allegan, Sunday, 6 September
Climate normal for this date — 60-year average.
Average high74°
Average low63°
Average precipitation0.11 in
Chance of precipitation35%
Record high86° (1990)
Record low51° (2011)
Mon, 0774° / 63°0.12
74 °
Allegan, Monday, 7 September
Climate normal for this date — 60-year average.
Average high74°
Average low63°
Average precipitation0.12 in
Chance of precipitation32%
Record high87° (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 Allegan, MI 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 Allegan, MI 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.