Herrin, IL Weather

Williamson County11:42 PM CDT37.80°N, 89.03°WElevation 420 ft

Current conditions

Clear
48°
Clear
Feels like 48°
High 75° Wednesday·Low 43° tonight
WindS 1 mph
Humidity100%
Dew point48°
Pressure30.29 inHg
Visibility10.0 mi
Cloud cover3%
UV index0 Low
Sunrise7:10 AM
Sunset6:13 PM

Observed at Marion - Williamson County Regional Airport · 47 min ago

Forecast

10-day

  • Tonight

    Clear, with a low around 43. West wind around 1 mph.

  • Wednesday

    Sunny. High near 75, with temperatures falling to around 73 in the afternoon. North northeast wind 0 to 3 mph.

  • Wednesday Night

    Mostly clear, with a low around 46. North wind around 1 mph.

National Weather Service forecast updated 21 min ago.

Hourly

Hourly forecast
  1. Now Clear 49°
  2. Wed12 AM Clear 48°
  3. 1 AM Clear 47°
  4. 2 AM Clear 46°
  5. 3 AM Clear 45°
  6. 4 AM Mostly Clear 44°
  7. 5 AM Clear 43°
  8. 6 AM Sunny 43°
  9. 7 AM Sunny 43°
  10. 8 AM Sunny 44°
  11. 9 AM Sunny 51°
  12. 10 AM Sunny 60°
  13. 11 AM Sunny 65°
  14. 12 PM Sunny 70°
  15. 1 PM Sunny 73°
  16. 2 PM Sunny 74°
  17. 3 PM Sunny 75°
  18. 4 PM Sunny 74°
  19. 5 PM Sunny 73°
  20. 6 PM Mostly Clear 70°
  21. 7 PM Mostly Clear 63°
  22. 8 PM Partly Cloudy 59°
  23. 9 PM Partly Cloudy 56°
  24. 10 PM Mostly Clear 54°

10-day forecast

Details
  1. TonightOct 20 Clear Clear43°
  2. WedOct 21 Sunny Sunny46°75°
  3. ThuOct 22 Sunny Sunny46°77°
  4. FriOct 23 Sunny Sunny45°75°
  5. SatOct 24 Mostly Sunny Mostly Sunny48°77°
  6. SunOct 25 Mostly Sunny Mostly Sunny49°78°
  7. MonOct 26 Mostly Sunny Mostly Sunny48°76°
  8. TueOct 27 Partly Sunny Partly Sunny70°
  9. WedOct 28 Cloudy Cloudy55°66°
  10. ThuOct 29 Cloudy Cloudy50°66°

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

Radar

Full map
Open the National Weather Service radar (the map here needs JavaScript).

Weather news in Illinois

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Air quality

40
Good
Ozone

Air quality is satisfactory, and air pollution poses little or no risk.

Farrar, MO reporting area · 1 hr ago. Data from AirNow (EPA and its state, local and tribal partners); preliminary and subject to change.

Sun & moon

Sunrise 7:10 AM
Sunset 6:13 PM
Daylight 11 h 3 min (−2 min 18 s tomorrow)
Waxing Gibbous · 74% lit
Moonrise 3:21 PM Moonset 1:17 AM
Full moon Oct 26 New moon Nov 9

Almanac

Monthly
Normal high / low69° / 43°
Record high91° (1963)
Record low22° (2022)
Wettest0.95 in (1926)
Yesterday72° / 37°
Month to date1.00 in (normal 2.10 in)

Carbondale Area, records since 1898. Normals 1991–2020. Data from NOAA's Regional Climate Centers (ACIS).

Nearby

Forecasters' discussion

From the National Weather Service office in PAH, issued 6 hrs ago

Key Messages

- Areas of fog, some possibly dense, will develop near bodies of water early Wednesday morning.

- Near to slightly above normal temperatures are forecast for the next seven days.

- No rainfall is forecast for the next seven days.

Update

Issued at 505 PM CDT Tue Oct 20 2026

Updated aviation discussion for 00z TAFS.

Discussion

Issued at 1119 AM CDT Tue Oct 20 2026

Sprawling high pressure centered over the eastern and northeast CONUS combined with stable H5 ridging over the southern and central CONUS will bring quiet and stable weather to the region for the next week. Temperatures will be nearly the same each day, with highs in the lower to middle 70s and lows in the middle to upper 40s. The only mentionable weather concern will be for shallow (and possibly briefly dense) fog development early Wednesday morning near bodies of water (lakes, rivers, ponds, etc.). Have added fog to the forecast for these areas.

Aviation

Issued at 505 PM CDT Tue Oct 20 2026

Shallow ground fog will again be possible early Wednesday morning, primarily near bodies of water. CGI is most likely terminal to be impacted. Otherwise VFR conditions with calm or very light NE winds and only a few high clouds (primarily in the west).

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.