A combination of an unusually cold air mass, calm wind and fresh snow cover brought very cold temperatures to much of western and central Wyoming. Temperatures as low as 19 below occurred in Yellowstone Park.
Every event with a place to put it; 12 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS RIW wrote it up.
A combination of an unusually cold air mass, calm wind and fresh snow cover brought very cold temperatures to much of western and central Wyoming. Temperatures as low as 19 below occurred in Yellowstone Park. Several stations had all time record lows for the month of April, including Riverton, Buffalo, Greybull and Worland, Wyoming. The record low temperature at Worland, Wyoming was especially noteworthy, since it broke a record that stood since 1947.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Riverton, WY wrote its last area forecast discussion before the first event at Apr 2, 3:12 PM MST, 8 hours 48 minutes earlier.
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</html>The national radar mosaic for the moment the first event began.
12 extreme cold/wind chill. Local standard time, as filed.
Very cold temperatures occurred in Yellowstone Park. The lowest temperature recorded was 19 below zero at Grant Village.
Very cold temperatures occurred in the Cody Foothills. The lowest temperature recorded was 7 below zero near Meeteetse, Wyoming.
Very cold temperatures occurred in Hot Springs County. The lowest temperature recorded was 2 below zero to the northeast of Thermopolis, Wyoming.
Very cold temperatures occurred in Washakie County, Wyoming. At the Worland, Wyoming airport, a low temperature of 2 degrees occurred. This is the all time low temperature for Worland,Wyoming, with records dating back to 1947.
Very cold temperatures occurred in Northern Johnson County. At the Buffalo, Wyoming Airport, a low temperature of 2 degrees tied the all-time April record low temperature.
Very cold temperatures occurred in southern Johnson County. The lowest temperature recorded was 5 below zero at Kaycee, Wyoming.
Very cold temperatures occurred in the Upper Wind River Basin. The cold temperatures included minus 5 degrees at DuBois, Wyoming and minus 9 degrees at Crowheart, Wyoming.
Very cold temperatures occurred in the Wind River Basin. The low temperature of 2 degrees at the Riverton, Wyoming airport was 2 degrees, the lowest record temperature for the month of April since records were kept since 1995.
Very cold temperatures occurred in the Lander, Wyoming Foothills. At the the Lander, Wyoming Airport, the low of 2 degrees was the 4th lowest April low temperature ever.
Very cold temperatures occurred in the Green Mountains. The cold temperatures included minus 2 degrees at Jeffrey City, Wyoming.
Very cold temperatures occurred in Natrona County. The cold temperatures included minus 5 degrees at the Natrona County airport, the second lowest April temperature recorded since records starting being kept in 1938.
Very cold temperatures occurred in the Upper Wind River Basin. The cold temperatures included minus 10 degrees at Daniel, Wyoming.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2020Every state in 2020This day in weather historyWarnings in Wyoming, April 2020
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 884363, 884364, 884365, 884366, 884367, 884368, 884369, 885067, 885068, 885069, 885070, 885071.