Algonquin, IL Monthly Weather

McHenry County4:29 PM CDT42.17°N, 88.29°WElevation 741 ft
← September

October 2026

Sun
Mon
Tue
Wed
Thu
Fri
Sat
163°/59°0.71 inAvg 66°/47°
267°/50°1.24 inAvg 66°/47°
363°/44°<0.01 inAvg 65°/46°
466°/46°Avg 65°/46°
569°/45°Avg 65°/45°
665°/48°Avg 64°/45°
769°/51°Avg 64°/45°
875°/48°Avg 63°/44°
968°/51°Avg 63°/44°
1066°/55°<0.01 inAvg 62°/44°
1175°/52°Avg 62°/43°
1277°/50°Avg 62°/43°
13Avg 61°/42°
1476°/60°0.19 inAvg 61°/42°
1562°/55°<0.01 inAvg 60°/42°
1663°/49°0.33 inAvg 60°/41°
1754°/35°0.04 inAvg 60°/41°
1856°/35°Avg 59°/41°
1961°/40°<0.01 inAvg 59°/40°
20 Sunny 68°/42°Avg 58°/40°
21 Patchy Fog then Sunny 70°/45°Avg 58°/40°
22 Sunny 70°/47°Avg 58°/39°
23 Sunny 67°/47°Avg 57°/39°
24 Mostly Sunny 68°/51°Avg 57°/39°
25 Partly Sunny 69°/48°Avg 56°/38°
26 Mostly Sunny then Slight Chance Rain Showers 65°/44°Avg 56°/38°
27 Cloudy 55°/43°Avg 56°/38°
28 Cloudy 52°/42°Avg 55°/37°
29 Sunny 53°/40°Avg 55°/37°
30Avg 54°/37°
31Avg 54°/36°
Average high66° (normal 63°)
Average low49° (normal 44°)
Warmest / coldest77° / 35°
Precipitation2.55 in (normal 2.01 in to date)
Record high today78° (1971)
Record low today20° (1964)

Observed: Barrington 3sw, 12 km away, records since 1962. Normals 1991–2020. Climate data from NOAA's Regional Climate Centers (ACIS); recent days are preliminary. Days ahead: the forecast.

Forecasts, observations and alerts in the United States come from the National Weather Service (NOAA); radar from NOAA's Multi-Radar Multi-Sensor system; satellite imagery from NASA's Global Imagery Browse Services (GIBS) and NOAA's GOES satellites; the map from the U.S. Geological Survey's National Map; air quality from AirNow (EPA and its partners); hurricane information from the National Hurricane Center; climate normals and records from NOAA's Regional Climate Centers (ACIS). Forecasts outside the United States and the UV index: MET Norway (CC BY 4.0); observations outside the U.S.: airport reports via NOAA's Aviation Weather Center. Place names: GeoNames (CC BY 4.0). Data are copied on a schedule and may lag the sources; for warnings that affect your safety, follow your local National Weather Service office and emergency officials. Weather news is drawn from the 4Search index and reflects what the press published. Terms of use.