Herrin, IL Weather

Williamson County3:22 PM CDT37.80°N, 89.03°WElevation 420 ft

Current conditions

Clear
72°
Clear
Feels like 70°
High 75°·Low 45°
WindCalm
Humidity35%
Dew point43°
Pressure30.24 inHg
Visibility10.0 mi
Cloud cover1%
UV index3 Moderate
Sunrise7:11 AM
Sunset6:12 PM

Observed at Marion - Williamson County Regional Airport · 1 hr ago

Forecast

10-day

  • This Afternoon

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

  • Tonight

    Areas of fog after 2am. Clear, with a low around 45. North northeast wind around 1 mph.

  • Thursday

    Areas of fog before 9am. Sunny. High near 77, with temperatures falling to around 75 in the afternoon. North wind 0 to 6 mph.

National Weather Service forecast updated 1 hr ago.

Hourly

Hourly forecast
  1. Now Sunny 75°
  2. 4 PM Sunny 74°
  3. 5 PM Sunny 73°
  4. 6 PM Clear 69°
  5. 7 PM Clear 63°
  6. 8 PM Clear 59°
  7. 9 PM Clear 57°
  8. 10 PM Clear 54°
  9. 11 PM Clear 52°
  10. Thu12 AM Clear 51°
  11. 1 AM Clear 50°
  12. 2 AM Patchy Fog 49°
  13. 3 AM Patchy Fog 48°
  14. 4 AM Areas Of Fog 47°
  15. 5 AM Areas Of Fog 46°
  16. 6 AM Areas Of Fog 46°
  17. 7 AM Areas Of Fog 45°
  18. 8 AM Areas Of Fog 47°
  19. 9 AM Sunny 53°
  20. 10 AM Sunny 63°
  21. 11 AM Sunny 68°
  22. 12 PM Sunny 73°
  23. 1 PM Sunny 75°
  24. 2 PM Sunny 76°

Daily forecast

Details
  1. TodayOct 21 Sunny Sunny45°75°
  2. ThuOct 22 Areas Of Fog then Sunny Areas Of Fog then Sunny46°77°
  3. FriOct 23 Sunny Sunny45°76°
  4. SatOct 24 Mostly Sunny Mostly Sunny47°77°
  5. SunOct 25 Partly Sunny Partly Sunny47°78°
  6. MonOct 26 Partly Sunny Partly Sunny48°77°
  7. TueOct 27 Partly Sunny Partly Sunny47°74°
  8. WedOct 28 Cloudy Cloudy55°66°
  9. 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
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Weather news in Illinois

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Air quality

46
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 7:11 AM
Sunset 6:12 PM
Daylight 11 h 1 min (−2 min 18 s tomorrow)
Waxing Gibbous · 80% lit
Moonrise 3:46 PM Moonset 2:19 AM
Full moon Oct 26 New moon Nov 9

Almanac

Monthly
Normal high / low68° / 43°
Record high89° (1963)
Record low18° (1952)
Wettest2.26 in (1945)
Yesterday74° / 43°
Month to date1.00 in (normal 2.23 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 3 hrs ago

Key Messages

- Areas of dense fog will continue late overnight into the morning hours near bodies of water.

- Generally clear and temperate conditions will remain through the weekend.

- A small chance of a shower exists early next week, though confidence is low.

Discussion

Issued at 1219 PM CDT Wed Oct 21 2026

An UL omega block has been established, with our CWA on the eastern edge of the 250 mb ridge as of 16z. As such, high surface pressure will be dominant until Monday at the earliest, leaving generally cloudless skies and seasonable, if not slightly above average, temperatures. Tuesday, long-range guidance suggests weak FROPA associated with the easterly progression of the UL trough, but vorticity and frontogenesis values are low, and 250 mb flow is only weakly perturbed. GFS and ECMWF 500 mb relative humidity prog <40%, so chances of widespread precipitation are minimal. A brief shower or two cannot be ruled out though, especially Tuesday morning in western parts of our coverage area.

Given weak surface flow, patchy areas of dense radiation fog are possible near bodies of water and in surrounding low-lying areas overnight through the morning. Widely scattered clouds tomorrow morning will not hinder the suns ability to quickly erode this fog, so expect the fog threat to be eliminated by 15z tomorrow.

Aviation

Issued at 1209 PM CDT Wed Oct 21 2026

High pressure will continue to bring calm or very light NE winds through the forecast period. Low-lying river valley fog development is expected again during the 11-13z Thursday period. Included this in the CGI and OWB TAFs where impacts are most likely. Otherwise, VFR conditions are expected.

Pah Watches

IL...None. MO...None. IN...None. KY...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.