Almost half of the U.S. has been in a drought since the start of 2021.

Compounding factors, including low rainfall and snowpack, climate change and persisting droughts from previous years, have escalated into extreme dryness.

The prolonged dryness means 30% of California's population is in a drought emergency, and the nation's two biggest reservoirs on the Colorado River — Lake Powell and Lake Mead — are two-thirds empty.

"What we see in our major reservoirs on the Colorado River really give us a good indication of water and drought in the West, and whether we're in a good or a tough spot," said John Berggren, a water policy analyst at Western Resource Advocates, a nonprofit organization. "And right now, we're definitely in the latter category."

Here's a rundown of what's happening and what may come next.

What is a drought?

The classic image that may come to mind is dry, cracked ground where perhaps a healthy river once flowed. Droughts can and do occur throughout every season of the year, and aren't dictated by temperature, but rather moisture levels.

A drought occurs when precipitation is lower than normal, leading to a water shortage, according to Brad Pugh, a meteorologist at the Climate Prediction Center, a federal agency.

There are five categories of drought severity. An abnormally dry drought can lead to short-term dryness, slowing crop growth and lingering water deficits, while an exceptional drought creates widespread crop loss and water emergencies.

Which areas of the U.S. are being affected?

Almost every part of the Western U.S. is in a drought. Montana, Idaho, Washington, Oregon, California, Nevada, Arizona and New Mexico are all experiencing extreme and exceptional droughts, the two most severe types, according to the U.S. Drought Monitor, a weekly drought map produced by the U.S. government and the University of Nebraska-Lincoln.

Colorado, Utah, North Dakota and Illinois are also facing drought conditions, said Curtis Riganti, a climatologist at the university's National Drought Mitigation Center.

Minnesota is drier than usual though not yet considered under extreme drought conditions. The state's row crops are growing ahead of schedule due to the warm weather while soil moisture levels are below normal, according to the U.S. Department of Agriculture's latest weekly crop report.

A spokesperson for the University of Minnesota Extension services said farmers are eager for rain but said it's still too early to know for certain if this growing season will be negatively affected by drought. A dry spell late in the summer is considered more dangerous for crops than one occurring in June.

Drought, heat waves and wildfire

Dryness from drought and the high temperature from heat waves have analysts worried about fires. As heat builds and soil dries out, the dry ground becomes a place for wildfires to spark and spread.

In the Northwest, massive wildfires last year burned more than 1.6 million acres, killing at least 12 people and forcing tens of thousands to evacuate. Thousands of homes were destroyed in the fires, which cloaked the region in thick smoke for weeks.

Washington state has responded to 475 blazes so far on public land since the beginning of the year, compared with 318 by this time last year, according to the state Department of Natural Resources.

Drought-parched vegetation and forests overstocked with trees from decades of fire suppression are a flammable mix, she said.

Analysts say drought can reduce cover, food and water sources, and habitat for wildlife. And droughts have caused some farmers to stop growing crops altogether.

In Oregon, native fish are dying and many farmers are cut off from their water supply.