The western United States is burning over 46 degrees Celsius and it’s not summer yet

In Lake Mead, which supplies water to 25 million people in three states in the southwest and Mexico, water levels have fallen to their lowest since the reservoir filled in the 1930s. In California, farmers abandoned their thirsty crops to save others, and local communities debate whether Tap water should be rationed.

In Texas, electrical grids are running while residents are turning on their air conditioners, and utilities are asking customers to turn off appliances to help prevent blackouts. In Arizona, Montana, and Utah, wildfires are burning.

And even summer has not yet come.

“We are still far from the peak of the wildfire season and the peak of the dry season,” said Daniel Swain, a climate scientist at the University of California, Los Angeles. “Things are likely to get worse before they get better.”

Global warming, caused by the burning of fossil fuels, has heated and dried the American West for years. Now the region is burning under a combination of the worst drought in two decades and an unprecedented heat wave.

With temperatures expected to continue to rise as nations struggle to control their greenhouse emissions, the Western United States will have to take difficult and costly steps to adapt. This includes redesigning cities to withstand extreme temperatures, conserving water, and engineering networks that do not fail in extreme weather conditions.

This month provided glimpses of whether states and cities are up to the task and showed that they still have a long way to go.

From Montana to Southern California, much of the West is experiencing unusually high temperatures. About 50 million Americans face heat-related warnings. Records have been set or broken in places like Palm Springs, Salt Lake City, and Billings, Montana.

Extreme heat is the clearest and deadliest sign of global warming. Last year, extreme heat killed at least 323 people in Maricopa County, including Phoenix, breaking a record so far.