Algonquin, IL Weather

McHenry County6:57 PM CDT42.17°N, 88.29°WElevation 741 ft

Current conditions

Clear
61°
Clear
Feels like 61°
High 70° Wednesday·Low 42° tonight
WindCalm
Humidity55%
Dew point45°
Pressure30.32 inHg
Visibility10 mi
Cloud cover2%
UV index0 Low
Sunrise7:12 AM
Sunset6:05 PM

Observed at Chicago / West Chicago, Dupage Airport · 47 min ago

Forecast

10-day

  • Tonight

    Patchy fog after 4am. Mostly clear, with a low around 42. East southeast wind 0 to 5 mph.

  • Wednesday

    Patchy fog before 8am. Sunny. High near 70, with temperatures falling to around 67 in the afternoon. West southwest wind 0 to 5 mph.

  • Wednesday Night

    Mostly clear, with a low around 45. South southwest wind around 0 mph.

National Weather Service forecast updated 9 hrs ago.

Hourly

Hourly forecast
  1. Now Clear 60°
  2. 7 PM Mostly Clear 56°
  3. 8 PM Mostly Clear 53°
  4. 9 PM Mostly Clear 51°
  5. 10 PM Mostly Clear 49°
  6. 11 PM Mostly Clear 48°
  7. Wed12 AM Mostly Clear 47°
  8. 1 AM Partly Cloudy 47°
  9. 2 AM Mostly Clear 46°
  10. 3 AM Partly Cloudy 45°
  11. 4 AM Patchy Fog 44°
  12. 5 AM Patchy Fog 43°
  13. 6 AM Patchy Fog 42°
  14. 7 AM Patchy Fog 42°
  15. 8 AM Mostly Sunny 45°
  16. 9 AM Mostly Sunny 51°
  17. 10 AM Mostly Sunny 57°
  18. 11 AM Sunny 62°
  19. 12 PM Sunny 65°
  20. 1 PM Sunny 68°
  21. 2 PM Sunny 69°
  22. 3 PM Sunny 69°
  23. 4 PM Sunny 70°
  24. 5 PM Sunny 67°

10-day forecast

Details
  1. TodayOct 20 Sunny Sunny42°68°
  2. WedOct 21 Patchy Fog then Sunny Patchy Fog then Sunny45°70°
  3. ThuOct 22 Sunny Sunny47°70°
  4. FriOct 23 Sunny Sunny47°67°
  5. SatOct 24 Mostly Sunny Mostly Sunny51°68°
  6. SunOct 25 Partly Sunny Partly Sunny48°69°
  7. MonOct 26 Mostly Sunny then Slight Chance Rain Showers Mostly Sunny then Slight Chance Rain Showers15%44°65°
  8. TueOct 27 Cloudy Cloudy43°55°
  9. WedOct 28 Cloudy Cloudy42°52°
  10. ThuOct 29 Sunny Sunny40°53°

Days after the National Weather Service's seven are MET Norway's outlook, a computer model with no forecaster's review.

Radar

Full map
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Air quality

56
Moderate
Fine particles (PM2.5)

Acceptable. Unusually sensitive people should consider limiting prolonged outdoor exertion.

Forecast

  • TueModerate
  • WedModerate
  • ThuModerate

North and West Suburbs (Chicago), IL reporting area · 57 min ago. Data from AirNow (EPA and its state, local and tribal partners); preliminary and subject to change.

Sun & moon

Sunrise 7:12 AM
Sunset 6:05 PM
Daylight 10 h 52 min (−2 min 41 s tomorrow)
Waxing Gibbous · 72% lit
Moonrise 3:26 PM Moonset 1:05 AM
Full moon Oct 26 New moon Nov 9

Almanac

Monthly
Normal high / low58° / 40°
Record high78° (1971)
Record low20° (1964)
Wettest1.81 in (1995)
Yesterday61° / 40°, <0.01 in
Month to date2.55 in (normal 2.12 in)

Barrington 3sw, records since 1962. Normals 1991–2020. Data from NOAA's Regional Climate Centers (ACIS).

Nearby

Forecasters' discussion

From the National Weather Service office in LOT, issued 4 hrs ago

Key Messages

- Areas of fog, including potentially dense fog, may develop again late tonight into early Wednesday morning in and near the Chicago metro.

- An extended period of dry and above to much above average temperatures is expected through the upcoming weekend.

Discussion

Issued at 226 PM CDT Tue Oct 20 2026

An Omega block that is in place over the CONUS is expected to persist through the end of the week. The associated ridge axis will only ever so slowly crawl eastward over the coming days, which will maintain broad surface high pressure across the region. As a result, dry conditions with an abundance of sunshine will continue through the remainder of the week with high temperatures remaining above to well above normal for this time of year. Daily lake breezes will cause the coolest (low- mid 60s) high temperatures to be observed near Lake Michigan each day.

Much like last night/early this morning, optimal radiational cooling conditions will likely allow for fog to develop late tonight into tomorrow morning and possibly again in the coming nights/mornings. This will particularly be the case in and near the Chicago metro within the footprint of the marine-influenced air brought inland during the daytime, where the fog could become dense once again.

There is pretty good ensemble agreement at this point in time that the blocking pattern will break down by early next week. This will allow for a cold front to drop through the region sometime on Monday or Tuesday, resulting in a return to cooler and more seasonable temperatures for the middle of next week. The frontal passage may bring a chance for precipitation to the area early-mid next week, but support for this across the latest suite of ensemble guidance is not ubiquitous, and there are considerable temporal differences with when this next potential opportunity for precipitation may arrive as well.

Ogorek

Aviation

Issued at 1255 PM CDT Tue Oct 20 2026

Key aviation forecast messages:

- IFR or lower VSBYs in BR/FG may develop again early WED AM.

The primary concern through the period is the potential for fog near Lake Michigan early Wednesday morning, some of which may become locally dense. Model guidance that performed well with this morning's dense fog depicts another round of fog development over a similar area and extends slightly farther southeast. Have accordingly included MDW with the reduced VSBYs as low as 1 SM with this update to hint at increasing confidence in fog development. If this signal persists and additional guidance begins to pick up on the potential for dense fog, LIFR (or lower) conditions may need to be introduced with later updates.

Otherwise winds will remain light (under 10 kt) initially out of the SE, turning E to ENE behind a weak lake breeze this afternoon. Winds then ease and become light and variable again overnight eventually settling into a SSW direction after daybreak Wednesday.

Petr

Lot Watches

IL...None. IN...None. LM...None.

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 4Conservative index and reflects what the press published. Terms of use.