KANSAS CITY, Mo. — Pack away the sidewalk tables and flip-flops; break out the boots and shovels.

Nature was showing its fickle side on Wednesday, with blizzard conditions, heavy snow and frigid air pounding parts of the Rockies and the Plains, just a day after the weather was sunny and idyllic. Schools and highways were shut down, hundreds of flights were canceled, and some communities braced for floods.

The storm, caused by a low-pressure system moving east from the Pacific Ocean, dropped temperatures by up to 50 degrees in places like Denver, where it was sunny and in the mid-70s on Tuesday but reached the mid-20s by Wednesday night. The low-pressure system was affecting areas from Colorado to Michigan, with heavy snow and thunderstorms, and even down into Texas, where dry conditions and high winds led to wildfire warnings.

While the whipsawing forecasts drew groans, they did not come as much of a surprise to those familiar with springtime in the Plains and the Rockies.