Summer is quickly becoming a brutal season: Last week alone, record-breaking June heat forced schools to close across the Northeast and slowed some trains, flooding caused bridges to collapse in the Midwest and inundated towns across three states, and tropical storm-force winds prompted disaster declarations for 51 Texas counties.

The threat of climate change lurks behind many recent events.

“Last year, of course, was the warmest year on record by a pretty large margin, and this year, so far, has been the warmest on record for this time of June,” Daniel Swain, a climate scientist at the University of California, Los Angeles and the National Center for Atmospheric Research, said at a briefing on Monday.

While it will take time for climate scientists to understand and calculate the impact of global warming on individual weather events, the science is clear that as the planet warms, the likelihood of extreme temperatures increases, and the risk of heavy rains increases because a warmer atmosphere can hold and release more moisture.

As a result, the effects of climate change will be more noticeable in the summer, Swain said.

“It’s not surprising that we’re seeing another wave of record-breaking heat and record-breaking rainfall. It’s exhausting, but I think it’s really important that we don’t forget or let it slip away,” he said. “And this heat is especially pronounced in the summer, because, of course, the Northern Hemisphere summer is when most people on the planet experience the hottest weather.”

Extremely heavy rainfall over the weekend flooded communities in at least 80 counties in Iowa, South Dakota and Minnesota, temporarily isolating the town of Spencer, Iowa, of 11,000 people from the rest of the state. About 2,000 structures, including hundreds of homes, were damaged in Iowa alone.