Crystal Lake, IL 60039 Weather

McHenry County2:30 AM CDT42.32°N, 88.45°W

Current conditions

Clear
52°
Clear
Feels like 52°
High 72°·Low 44° tonight
WindW 3 mph
Humidity77%
Dew point45°
Pressure30.24 inHg
Visibility10.0 mi
Cloud cover8%
UV index0 Low
Sunrise7:15 AM
Sunset6:03 PM

Observed at De Kalb Taylor Municipal Airport · 1 hr ago

Forecast

10-day

  • Tonight

    Patchy fog after 3am. Mostly clear, with a low around 44. Wind around 0 mph.

  • Thursday

    Patchy fog before 9am. Sunny. High near 72, with temperatures falling to around 70 in the afternoon. Northeast wind 0 to 5 mph.

  • Thursday Night

    Partly cloudy, with a low around 46. East northeast wind 0 to 5 mph.

National Weather Service forecast updated 5 hrs ago.

Hourly

Hourly forecast
  1. Now Mostly Clear 47°
  2. 3 AM Patchy Fog 47°
  3. 4 AM Patchy Fog 46°
  4. 5 AM Patchy Fog 45°
  5. 6 AM Patchy Fog 44°
  6. 7 AM Patchy Fog 45°
  7. 8 AM Patchy Fog 46°
  8. 9 AM Sunny 52°
  9. 10 AM Sunny 60°
  10. 11 AM Sunny 64°
  11. 12 PM Sunny 68°
  12. 1 PM Sunny 70°
  13. 2 PM Sunny 71°
  14. 3 PM Sunny 72°
  15. 4 PM Sunny 71°
  16. 5 PM Sunny 70°
  17. 6 PM Mostly Clear 66°
  18. 7 PM Mostly Clear 60°
  19. 8 PM Mostly Clear 55°
  20. 9 PM Mostly Clear 53°
  21. 10 PM Mostly Clear 51°
  22. 11 PM Partly Cloudy 50°
  23. Fri12 AM Partly Cloudy 49°
  24. 1 AM Partly Cloudy 48°

10-day forecast

Details
  1. TonightOct 21 Mostly Clear then Patchy Fog Mostly Clear then Patchy Fog44°
  2. TodayOct 22 Patchy Fog then Sunny Patchy Fog then Sunny46°72°
  3. FriOct 23 Mostly Sunny Mostly Sunny49°71°
  4. SatOct 24 Partly Sunny Partly Sunny51°70°
  5. SunOct 25 Partly Sunny Partly Sunny51°72°
  6. MonOct 26 Partly Sunny Partly Sunny15%47°66°
  7. TueOct 27 Slight Chance Rain Showers Slight Chance Rain Showers23%45°61°
  8. WedOct 28 Slight Chance Rain Showers then Partly Sunny Slight Chance Rain Showers then Partly Sunny15%63°
  9. ThuOct 29 Cloudy Cloudy38°54°
  10. FriOct 30 Mostly sunny Mostly sunny39°56°

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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Weather news near Crystal Lake

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Air quality

80
Moderate
Fine particles (PM2.5)

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

Forecast

  • ThuModerate
  • FriModerate

North and West Suburbs (Chicago), IL reporting area · 1 hr ago. Data from AirNow (EPA and its state, local and tribal partners); preliminary and subject to change.

Sun & moon

Sunrise 7:15 AM
Sunset 6:03 PM
Daylight 10 h 47 min (−2 min 41 s tomorrow)
Waxing Gibbous · 83% lit
Moonrise 4:09 PM Moonset 3:16 AM
Full moon Oct 26 New moon Nov 9

Almanac

Monthly
Normal high / low60° / 40°
Record high80° (2024)
Record low24° (1982)
Wettest1.48 in (1972)
Month to date3.11 in (normal 2.15 in)

Lake Geneva Wwtp, records since 1945. Normals 1991–2020. Data from NOAA's Regional Climate Centers (ACIS).

Nearby

Forecasters' discussion

From the National Weather Service office in LOT, issued 2 hrs ago

Key Messages

- The dry and unseasonably mild weather will continue through the upcoming weekend.

Discussion

Issued at 136 PM CDT Wed Oct 21 2026

An anomalously strong mid-level ridge over the central CONUS will anchor omega blocking across much of North America over the next several days. Meanwhile, an elongated surface ridge extending from the Lower Mississippi River Valley to the Canadian Maritimes is in the processes of congealing with another expansive high pressure shifting toward the Upper Great Lakes. As a result, quiet weather with unseasonably warm conditions will continue through the upcoming weekend. As was observed the past few mornings, generally clear skies and light/calm winds should promote shallow fog across primarily interior northern Illinois late tonight through sunrise Thursday.

The blocking pattern will slowly break down early next week as the ridge flattens and a southwestern upper-level low begins to meander toward the central CONUS. A series of smaller troughs on the periphery of a developing longwave trough across the north Pacific and western Canada will eventually pick up the southwestern low. Consensus guidance suggests that the influence of the low on our area could occur as early as Monday night, but more likely Tuesday and Wednesday. Cooler and more seasonable conditions would accompany this system.

Kluber

Aviation

Issued at 1154 PM CDT Wed Oct 21 2026

- Brief period of some shallow ground fog possible early this morning, primarily at RFD and GYY - There's around a 30% chance of dense fog adjacent to the lake into mainly northeast IL tonight.

Surface dewpoint depressions are generally running several degrees larger than last night at ORD, DPA, and MDW, so potential for VSBY restrictions at those terminals this morning is more more limited. Maintained TEMPOs for IFR/low end MVFR VSBY at GYY and RFD where dewpoint depressions are smaller and on pace with last night. If and where any VSBY restrictions occur early this morning, conditions would likely return to VFR by around 14z.

Calm to very light northeast winds will be the rule today, which should allow for a lake breeze to move inland. Behind this lake breeze, northeast winds of 5-9kt are likely at ORD, MDW, and GYY. An increase in moisture behind this lake breeze opens the door to a potential dense fog problem over primarily northeast IL tonight. Confidence is low, so held off on introducing anything into the TAFs now, but there is probably around 30% chance of LIFR/VLIFR conditions into ORD, MDW, and possibly GYY and DPA.

- Izzi

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