Weather Alerts For Clarksburg, MO

# SUMMARY -------------------- SEVERE THUNDERSTORM WATCH 454 REMAINS VALID UNTIL 7 PM CDT THIS EVENING FOR THE FOLLOWING AREAS IN ILLINOIS THIS WATCH INCLUDES 4 COUNTIES IN SOUTHWEST ILLINOIS MADISON MONROE RANDOLPH SAINT CLAIR IN MISSOURI THIS WATCH INCLUDES 17 COUNTIES IN CENTRAL MISSOURI BOONE CALLAWAY COLE MONITEAU OSAGE IN EAST CENTRAL MISSOURI CRAWFORD FRANKLIN GASCONADE JEFFERSON MONTGOMERY SAINT CHARLES SAINT LOUIS SAINT LOUIS CITY WARREN WASHINGTON IN SOUTHEAST MISSOURI SAINT FRANCOIS SAINTE GENEVIEVE THIS INCLUDES THE CITIES OF ALTON, BELLEVILLE, CAHOKIA, CHESTER, COLUMBIA, EDWARDSVILLE, FARMINGTON, FULTON, JEFFERSON CITY, SAINT CHARLES, SAINT LOUIS, SPARTA, SULLIVAN, UNION, AND WASHINGTON. # DETAILS -------------------- ISSUED AT Saturday, July 4, 2026 at 3:23 PM CDT ISSUED BY NATIONAL WEATHER SERVICE ST LOUIS MO HEADER WATCH COUNTY NOTIFICATION FOR WATCH 454

# HEADLINE -------------------- EXTREME HEAT WARNING REMAINS IN EFFECT UNTIL 8 PM CDT THIS EVENING # DETAILS -------------------- WHAT Dangerously hot conditions with heat index values up to 105. WHERE Portions of south central and southwest Illinois and central, east central, and southeast Missouri. WHEN Until 8 PM CDT this evening. IMPACTS Heat related illnesses increase significantly during extreme heat and high humidity events. ISSUED AT Saturday, July 4, 2026 at 3:55 AM CDT ISSUED BY National Weather Service St Louis MO HEADER URGENT - WEATHER MESSAGE # PRECAUTIONARY/PREPAREDNESS ACTIONS -------------------- Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. Young children and pets should never be left unattended in vehicles under any circumstances. Take extra precautions if you work or spend time outside. When possible reschedule strenuous activities to early morning or evening. Know the signs and symptoms of heat exhaustion and heat stroke. Wear lightweight and loose fitting clothing when possible. To reduce risk during outdoor work, the Occupational Safety and Health Administration recommends scheduling frequent rest breaks in shaded or air conditioned environments. Anyone overcome by heat should be moved to a cool and shaded location. Heat stroke is an emergency! Call 9 1 1. # AREAS AFFECTED -------------------- Monroe IL, Montgomery MO, Saint Louis MO, Boone MO, Callaway MO, Clinton IL, Cole MO, Franklin MO, Gasconade MO, Jefferson MO, Madison IL, Moniteau MO, Osage MO, Randolph IL, Saint Charles MO, Saint Clair IL, Saint Louis City MO, Sainte Genevieve MO, Warren MO, Washington IL Including the cities of Columbia, Washington, Cahokia, Fulton, Jefferson City, Chester, Sullivan, Saint Louis, Alton, Edwardsville, Union, Saint Charles, Sparta, and Belleville

Closest strike: 6.54 miles Stay Alert! Remain in a safe area until there has been no lightning within 10 miles of this location for 30 minutes. Please be aware that lightning activity can remain high even when a storm is moving away from your location. Even if rain has stopped, do not leave your safe area until WeatherBug indicates that lightning is more than 10 miles away from this selected location. IF OUTDOORS Avoid water, high ground, and open spaces. Avoid all metal objects including electric wires, fences, and machinery. Find a safe area in a building or in a fully enclosed vehicle with the windows completely shut. Unsafe places include underneath canopies, small picnic or rain shelters, convertibles, or near trees. IF INDOORS Avoid water and stay away from doors and windows. Avoid using a hard line telephone. Take off headphones. Turn off, unplug, and stay away from appliances, computers, power tools, and TV sets. Lightning may strike exterior electric and phone lines, inducing shocks to inside equipment.

There is a Slight Severe Storm Risk for your location. Continue reading for today's outlook from the National Weather Service's Storm Prediction Center. -------------------- National Severe Storm Outlook THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE SOUTHERN PLAINS AND MID ATLANTIC THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF THE CENTRAL HIGH PLAINS AND FROM THE SOUTHERN HIGH PLAINS TO SOUTHERN NEW ENGLAND SUMMARY Clusters of storms will continue to move across parts of the Allegheny Plateau into the Mid-Atlantic, with potential for numerous damaging wind gusts. Additional severe thunderstorms are still expected across the Great Plains this afternoon and evening, posing a risk for severe wind gusts and large hail. 20Z Update A cold-pool-driven MCS, with a history of measured 50+ kt gusts and wind damage, continues to rapidly propagate eastward across central MO. While deep-layer shear is quite modest over the Ozarks, a pronounced baroclinic boundary is draped across central MO into the St. Louis Metropolitan area. The MCS has likely maintained its intensity thus far by riding this boundary and ingesting some vorticity for bookend vortex and rear-inflow jet maintenance. It is unclear how long this MCS will remain strong/organized given the lack of ambient deep-layer shear. However. surface temperatures on the warm side of the boundary exceeding 90 F, amid mid 70s F dewpoints, is yielding a gradient of 2500-4500 J/kg SBCAPE, which should support some severe gust threat for this MCS for at least the next few hours. As such, 30 percent wind probabilities have been added ahead of the MCS. Guidance consensus, including early depictions from WoFS output, suggests that an MCS will quickly surge southeastward across portions of the southern Plains after initiating along the KS/OK border late this afternoon. The farther southeast initiation (given the current position of the surface outflow boundary left behind from the previous MCS), and southeastward surging potential, it appears that the greatest wind threat will exist into east-central OK. 30 percent/CIG1 wind probabilities have been extended into this region. Five percent hail probabilities have been added across portions of the lower Hudson Valley. Here, MRMS mosaic MESH data suggests that marginally severe hail may already be falling with the more robust storms over northern PA. Furthermore, stronger mid-level flow is grazing the lower Hudson Valley, contributing to 30-40 kts of effective bulk shear amid 1000+ J/kg MLCAPE, which should be adequate to support a continued hail threat. Otherwise, the previous forecast remains on track, including the potential for numerous damaging to occasionally severe gusts expected across portions of the Mid Atlantic into southern New England through the afternoon and evening hours. Mostly minor adjustments have been made to the remainder of the outlook to account for guidance consensus and observations.