O'Fallon, MO Weather

Saint Charles County3:26 PM CDT38.81°N, 90.70°WElevation 541 ft

Current conditions

Sunny
75°
Sunny
Feels like 75°
High 75°·Low 48°
WindE 2 mph
Humidity41%
Dew point50°
Cloud cover1%
UV index3 Moderate
Sunrise7:20 AM
Sunset6:16 PM

Forecast for this hour (no station report in the last two hours)

Forecast

10-day

  • Thursday

    Sunny. High near 75, with temperatures falling to around 71 in the afternoon. Northeast wind around 2 mph.

  • Thursday Night

    Clear, with a low around 48. East wind around 2 mph.

  • Friday

    Sunny, with a high near 76.

National Weather Service forecast updated 1 day ago.

Hourly

Hourly forecast
  1. Now Sunny 75°
  2. 4 PM Sunny 74°
  3. 5 PM Sunny 71°
  4. 6 PM Clear 67°
  5. 7 PM Clear 64°
  6. 8 PM Clear 61°
  7. 9 PM Clear 59°
  8. 10 PM Clear 57°
  9. 11 PM Clear 55°
  10. Fri12 AM Clear 54°
  11. 1 AM Clear 53°
  12. 2 AM Clear 52°
  13. 3 AM Clear 51°
  14. 4 AM Clear 51°
  15. 5 AM Clear 49°
  16. 6 AM Sunny 48°
  17. 7 AM Sunny 48°
  18. 8 AM Sunny 52°
  19. 9 AM Sunny 57°
  20. 10 AM Sunny 62°
  21. 11 AM Sunny 66°
  22. 12 PM Sunny 70°
  23. 1 PM Sunny 73°
  24. 2 PM Sunny 75°

10-day forecast

Details
  1. TonightOct 20 Mostly Clear Mostly Clear47°
  2. WedOct 21 Mostly Sunny Mostly Sunny49°74°
  3. TodayOct 22 Sunny Sunny48°75°
  4. FriOct 23 Sunny Sunny49°76°
  5. SatOct 24 Mostly Sunny Mostly Sunny52°77°
  6. SunOct 25 Mostly Sunny Mostly Sunny52°79°
  7. MonOct 26 Partly Sunny Partly Sunny49°74°
  8. TueOct 27 Partly Sunny Partly Sunny67°
  9. WedOct 28 Cloudy Cloudy0.02 in41°57°
  10. ThuOct 29 Sunny Sunny36°57°

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 Missouri

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Air quality

78
Moderate
Coarse particles (PM10)

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

Saint Louis, 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 7:20 AM
Sunset 6:16 PM
Daylight 10 h 56 min (−2 min 22 s tomorrow)
Waxing Gibbous · 87% lit
Moonrise 4:17 PM Moonset 3:28 AM
Full moon Oct 26 New moon Nov 9

Almanac

Monthly
Normal high / low67° / 47°
Record high86° (2020)
Record low25° (1976)
Wettest1.91 in (2009)
Yesterday76° / 48°
Month to date1.76 in (normal 2.05 in)

St Louis Area, records since 1874. Normals 1991–2020. Data from NOAA's Regional Climate Centers (ACIS).

Nearby

Forecasters' discussion

From the National Weather Service office in LSX, issued 1 hr ago

Key Messages

- Dry and seasonably warm conditions will persist through the weekend.

Short Term

Issued at 219 PM CDT Thu Oct 22 2026

A slow-moving upper-level ridge will dominate the Mid-Mississippi River Valley through the weekend with dry conditions continuing and only slight variations in above average temperatures. With a gradual exit of the surface high pressure center extending into the CWA this afternoon, the balance of airmass modification and subtle southeasterly low-level CAA through Friday followed by waves of upper-level clouds on Saturday and Sunday combined with weak southerly WAA will contribute to only slight fluctuations of high temperatures within the 70s F. Each night, the most favorable radiational cooling and coolest low temperatures in the 40s F will also become more and more confined to river valleys and southeastern MO/southwestern IL, closest to the high pressure and where clouds will be less prevalent and/or thinner. Patchy river valley fog is expected again Friday morning and potentially Saturday morning but coverage should be less.

Long Term

Issued at 219 PM CDT Thu Oct 22 2026

Global model guidance diverges considerably early to mid-next week in the evolution of an upper-level trough that propagates into the central CONUS Monday into Tuesday as the Omega Block breaks down. The track, amplitude, and tilt of this trough vary across guidance including whether an associated cold front passes through the CWA Tuesday or early Wednesday, enters and then stalls in the CWA, or stalls before reaching the CWA altogether. Accordingly, the NBM interquartile range increases to between 7 and 15 F Tuesday onward, with the 75th percentile remaining steady and the 25th percentile cooling closer to average. If the front reaches the CWA, showers will also become possible, with greatest probabilities of measurable rainfall in global ensemble models across central/northeastern MO and west-central IL at 30 to 50 percent. However, a widespread, substantial rainfall appears unlikely in the ranges of current scenarios. The aforementioned uncertainties persist through the end of the forecast period, late next week.

Aviation

Issued at 1211 PM CDT Thu Oct 22 2026

Dry and VFR flight conditions will persist through the TAF period with the exception of river valley fog again Friday morning. KSUS and KCPS are most favored for a short period of impacts from fog around sunrise Friday. Winds will remain light and eventually become more southeasterly to southerly on Friday.

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.