The threat of strong tornadoes, damaging hail and high winds is highest in the upper Midwest through Monday night. Severe weather and heavy rain will then stretch from the Great Lakes to the Southern Plains on Tuesday.

May is when tornado activity typically reaches its peak for the year. The Plains and Midwest find themselves in the greatest threat area as tornado counts climb to their highest totals annually. But as some recent years have shown, the month of May doesn’t always live up to expectations. Check out why some years have quieter Mays while others push the peak month well beyond the average.

Dramatic video shows how severe storms spawned a huge tornado in northwest Nebraska on Sunday. The twister derailed a train near Ashby, knocking over as many as 130 railcars.

A travel disaster played out Monday in several western European countries when a widespread blackout occurred in parts of Spain, France and Portugal. Subways went dark and traffic lights didn’t work, wreaking havoc in several large cities. Watch this video to see some of those scenes and learn more about how weather may play a factor.

Here's your latest monthly temperature and precipitaiton forecast for May.