Millions of Americans were under the threat of flash floods this Memorial Day weekend as heavy rain was forecast for waterlogged parts of Texas, Arkansas and the southern Plains.
Thunderstorms in the Midwest, Plains, Texas threatened to bring hail, wind and even isolated tornadoes on Saturday and Sunday, the Weather Channel said.
Average rainfall of up to three inches is possible over the next week in Texas, Oklahoma, Kansas, Missouri and parts of Louisiana and Arkansas, with high spots of 5 inches more possible.
"Additional flash flooding is likely with already saturated grounds and creeks, streams and rivers at bank full," said Weather Channel forecaster Brian Fortier.
Oklahoma City is only 0.6 inches of rain away from setting a record for its wettest month ever recorded.
Weather service forecaster Matt Stalley in Fort Worth, Texas, said people camping or on the waterways should take extra care. "There's quite a bit of danger now with the current situation. There's a lot of river and lake closures because of all the debris that's in the water that gets picked up by these floodwaters. There's additional threats for flash flooding for people that are out camping," Stalley said.
This article originally appeared on NBCNews.com.