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Byrnes Mill, MO Weather
Current conditions
Observed at St. Louis, Spirit Of St. Louis Airport · 56 min ago
Forecast
10-day-
Today
Patchy fog before 9am. Sunny, with a high near 76. Southeast wind 0 to 3 mph.
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Tonight
Mostly clear, with a low around 46. Southeast wind 0 to 3 mph.
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Saturday
Sunny, with a high near 76. Southeast wind 0 to 3 mph.
National Weather Service forecast updated 9 hrs ago.
Hourly
Hourly forecast- Now75°
- 4 PM76°
- 5 PM74°
- 6 PM71°
- 7 PM67°
- 8 PM61°
- 9 PM59°
- 10 PM57°
- 11 PM56°
- Sat12 AM55°
- 1 AM54°
- 2 AM51°
- 3 AM51°
- 4 AM49°
- 5 AM48°
- 6 AM48°
- 7 AM46°
- 8 AM48°
- 9 AM52°
- 10 AM62°
- 11 AM67°
- 12 PM71°
- 1 PM73°
- 2 PM74°
10-day forecast
Details- TodayOct 23Patchy Fog then Sunny46°76°
- SatOct 24Sunny46°76°
- SunOct 25Mostly Sunny48°79°
- MonOct 26Partly Sunny48°77°
- TueOct 27Partly Sunny48°75°
- WedOct 28Mostly Sunny50°76°
- ThuOct 29Mostly Sunny10%48°76°
- FriOct 30Mostly sunny43°65°
- SatOct 31Partly cloudy48°70°
- SunNov 1Partly cloudy55°77°
Days after the National Weather Service's seven are MET Norway's outlook, a computer model with no forecaster's review.
Radar
Full mapWeather news near Byrnes Mill
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Air quality
Acceptable. Unusually sensitive people should consider limiting prolonged outdoor exertion.
Saint Louis, MO reporting area · 2 hrs ago. Data from AirNow (EPA and its state, local and tribal partners); preliminary and subject to change.
Sun & moon
Almanac
MonthlyWeldon Spring Nws, records since 1957. Normals 1991–2020. Data from NOAA's Regional Climate Centers (ACIS).
Nearby
- St. Louis 39 km
- O'Fallon 43 km
- Saint Charles 39 km
- Saint Peters 40 km
- Florissant 45 km
- Chesterfield 25 km
- Belleville 53 km
- Oakville 24 km
- Wildwood 18 km
- Wentzville 48 km
- University City 34 km
- Ballwin 18 km
Forecasters' discussion
From the National Weather Service office in LSX, issued 1 hr ago
Key Messages
- High pressure remains in place allowing for our dry and warm weather continues well into next week.
Short Term
Issued at 148 PM CDT Fri Oct 23 2026
An upper-level ridge will remain positioned over the Mid-Mississippi River Valley through Sunday, stagnated by the configuration of the wave pattern into an Omega Block. This pattern will result in very little change in sensible weather from day to day with seasonably warm temperatures and dry conditions. The only change through the weekend will be the very slow departure of a surface high pressure center and upper-level clouds of varying thickness streaming overhead by Saturday through Sunday. The most pronounced nocturnal radiational cooling during the period will be across southeastern MO/southwestern IL and/or river valleys with low temperatures in the 40s F and patchy morning fog, mainly low temperatures in the 50s F elsewhere. High temperatures will continue to be in the 70s F, near 80 F on Sunday depending on the thickness of cloud cover.
Long Term
Issued at 148 PM CDT Fri Oct 23 2026
Global model guidance is coming into better agreement on the ejection of an upper-level trough into the Central/Northern Plains and Upper Midwest Monday through Tuesday as the Omega Block breaks down. With this track of the trough, it is increasingly likely that the associated cold front does not reach the CWA, favoring similar, seasonably warm temperatures continuing along with dry conditions.
It is not until late next week now, that there are any signs for our sensible weather to change with varying signals for an upper-level trough to propagate into the north-central CONUS. However, the track and amplitude of the trough is uncertain which will influence its ability to force an associated cold front east/southeastward. If the front reaches the CWA, it would be accompanied by an opportunity for rain and temperatures cooling closer to average late next week. If the front fails to reach the CWA, there would be no clear catalyst for seasonably warm temperatures and dry conditions to end. Ensemble model guidance cluster analysis depicts these scenarios all being valid possible outcomes at this point. Taking all scenarios into consideration, probabilities of measurable rainfall range from 20 to 50 percent Thursday, onward, along with NBM interquartile ranges increasing to between 10 and 20 F.
Aviation
Issued at 1147 AM CDT Fri Oct 23 2026
Aside from another round of fog in area river valleys Saturday morning potentially impacting KSUS and KCPS, dry and VFR flight conditions will prevail. Winds are expected to remain light and either southerly/southeasterly or variable.
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.