Torrential rain events and the flooding they cause are nothing new.  Global warming, however, is helping to make them more likely.

According to the most recent National Climate Assessment, heavy rain events – defined as the heaviest 1% of all rain events – have become heavier and more frequent across most of the US. The greatest increases have been observed in the northeast, mid-west, and southeast.

Climate scientists attribute this increase in heavy precipitation to our warming atmosphere. Simply put, warm air holds more moisture than cold air. And, the more moisture that builds up in the air, the more rain can fall.

The relentless rain and deadly floods in Texas last month made national headlines, but there are many other examples of similar events in the recent past. In September 2013, Colorado experienced catastrophic flooding caused by overwhelming amounts of rain in a short period of time. Locally, here in the NYC area, the town of Islip on Long Island saw more than 13 inches of rainfall in a single day last August. That equates to 29% of their average annual rainfall. The damage caused by that single event was estimated at $35 million.

As our global temperature continues to rise, experts say we should expect to see more extreme rain events, even in areas where overall precipitation is projected to decrease. In other words, when it rains, it will likely pour.

The map shows percent increases in the amount of precipitation falling in very heavy events  from 1958 to 2012 for each region of the continental United States. These trends are larger than natural variations for the Northeast, Midwest, Puerto Rico, Southeast, Great Plains, and Alaska. The trends are not larger than natural variations for the Southwest, Hawai‘i, and the Northwest. Credit: 2014 US National Climate Assessment