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Arnold, MO Weather
Current conditions
Observed at St. Louis Downtown Airport · 1 hr ago
Forecast
10-day-
Today
Sunny, with a high near 72. Southeast wind 0 to 5 mph.
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Tonight
Mostly clear, with a low around 47. Southeast wind 0 to 3 mph.
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Wednesday
Sunny, with a high near 72. East wind 0 to 3 mph.
National Weather Service forecast updated 1 hr ago.
Hourly
Hourly forecast- Now46°
- 9 AM51°
- 10 AM59°
- 11 AM64°
- 12 PM67°
- 1 PM70°
- 2 PM71°
- 3 PM72°
- 4 PM71°
- 5 PM70°
- 6 PM68°
- 7 PM63°
- 8 PM59°
- 9 PM57°
- 10 PM55°
- 11 PM54°
- Wed12 AM53°
- 1 AM51°
- 2 AM50°
- 3 AM51°
- 4 AM48°
- 5 AM48°
- 6 AM48°
- 7 AM47°
10-day forecast
Details- TodayOct 20Sunny47°72°
- WedOct 21Sunny46°72°
- ThuOct 22Sunny48°76°
- FriOct 23Sunny47°75°
- SatOct 24Mostly Sunny51°76°
- SunOct 25Partly Sunny51°78°
- MonOct 26Partly Sunny48°74°
- TueOct 27Cloudy57°69°
- WedOct 28Cloudy53°62°
- ThuOct 29Cloudy50°61°
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 Arnold
More weather news- St. Louis Weather Forecast Friday Through Thursday
St. Louis is trading late-summer warmth for a blustery fall reset Friday: mostly cloudy skies, a high near 55, and northwest winds around 17 mph with gusts up to 33 mph. A few rain showers could move through after 3…
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How frost this weekend could kickstart the emergence of fall foliageIf you have been waiting for vibrant red and purple leaves to take over Mid-Missouri, this weekend is the ultimate make-or-break moment. We are officially entering our prime window for autumn color, but the drastic…
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First Alert Weather Day Today: Low Severe Storm Chance 2 - 7PMKMOV - Outlying Areas Could See Frost Saturday AM and Sunday AM Today: Expect lots of cloud cover today with temperatures nearing 80°. Isolated Severe Storms Remain Possible this Afternoon from 2PM- 7PM: This is a…
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First Alert Weather Day Today: Low Severe Storm Chance This Afternoon-Early EveningKMOV - Outlying Areas Could See Frost Saturday AM and Sunday AM Today: Scattered showers and storms push through the region during the morning hours. Temperatures remain into the upper 60s and lower 70s during this…
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Damaging Winds Possible in Illinois and Missouri ThursdayParts of Missouri and most of Illinois are likely to experience the type of thunderstorm you'd expect to see during the Spring months. Forecasters are warning of a possible damaging wind event that will likely leave…
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This week's record heat caps hottest Jan.-Sept. on record in USIf it feels like summer never left, the numbers back you up. This week brought a fresh wave of record-breaking heat across the country, even as calendars flip toward Halloween. In a word: hot. According to U.S. National…
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Cold Front Ends Record October Heat Across the United StatesRecord-breaking October warmth across the central and eastern United States is giving way to a sharp cooldown, with a powerful cold front expected to bring rain, strong winds and scattered temperatures in the 40s by the…
- Daily high-temperature records broken or tied on October 13 across parts of the central U.S.
Five daily high-temperature records were broken and one was tied at six sites across Kansas, Oklahoma, Missouri and Illinois on October 13, 2026. Temperatures at the sites reached 32.8–33.9°C (91–93°F), or 9.4–13.3°C…
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St. Louis hits record high of 93 degrees in mid-OctoberSt. Louis reached a record high of 93 degrees on Tuesday. ST. LOUIS, Mo. (First Alert 4) - St. Louis reached a record high of 93 degrees on Tuesday. Temperatures in the 90s arrived as some seasonal preparations…
- Weather whiplash incoming: Record October heat could flip to first snow
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Air quality
People with heart or lung disease, older adults, children and teenagers should reduce prolonged or heavy exertion outdoors.
Saint Louis, MO reporting area · 29 min ago. Data from AirNow (EPA and its state, local and tribal partners); preliminary and subject to change.
Sun & moon
Almanac
MonthlySt Charles 7 Ssw, records since 1975. Normals 1991–2020. Data from NOAA's Regional Climate Centers (ACIS).
Nearby
- St. Louis 27 km
- O'Fallon 50 km
- Saint Charles 40 km
- Saint Peters 46 km
- Florissant 40 km
- Chesterfield 31 km
- Belleville 36 km
- Oakville 8 km
- Wildwood 30 km
- Wentzville 59 km
- University City 26 km
- Ballwin 23 km
Forecasters' discussion
From the National Weather Service office in LSX, issued 2 hrs ago
Key Messages
- Dry and seasonably warm conditions will persist through the end of the week.
Short Term
Issued at 227 AM CDT Tue Oct 20 2026
The forecast for the next several days can be summed up in one phrase - status quo. With an omega block in place in the mid-levels and high pressure stationed over the eastern CONUS at the surface, there is no reason for our sensible weather to change. The small increases in temperature we expect over the week can be attributed to persistent insolation rather than any sort of advection or dynamical reasoning. High clouds blowing into the region from the southern Plains may enter Mid-Missouri slightly before peak heating, which would prevent that area from gaining that degree or two of warmth this afternoon - a negligible difference on human skin. In all, the forecast today calls for highs around 70 degrees with very little wind and plenty of sun. Add a degree and we have the forecast for Wednesday as well. The high clouds and warmer afternoon will support higher low temperatures tonight for our Missouri counties. To the east where skies will be clearer for longer, radiational cooling is expected to create similar conditions to this morning.
Long Term
Issued at 227 AM CDT Tue Oct 20 2026
The forecast from Wednesday night through the end of the week is the same as that of today and tomorrow. Widespread 70s increase a degree or two each day unless warming is perturbed by high clouds. Late in the week mid-level ridging will be shoved eastward and flattened as a longwave trough strengthens over the Four Corners region. This system is forecast to drive a cold front into the Midwest late Saturday into Sunday, but latest model guidance indicates the front will pivot into a more west-east orientation before it reaches Missouri/central Illinois. This would keep accompanying rain and cold air to our north and lengthen the duration of our warm streak. Ensembles, aside from the GEFS, appear to support this solution. 850 mb temperatures Sunday into Monday are still forecast to be about 10C - the same as today - so a drastic cooldown within that period is not likely if the models are correct. Beyond that guidance diverges, and that's reliant on if the cold front does push through the CWA or not Monday into Tuesday. The NBM high temperature IQRs reflect the uncertainty quite well, with KSTL jumping from a 4 degree split on Sunday to a 12 degree split by Tuesday.
Aviation
Issued at 604 AM CDT Tue Oct 20 2026
After the morning river and valley fog dissipates, dry and VFR conditions with light winds will prevail through the remainder of the period.
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.