UC San Diego researchers say deadly heat waves are becoming more frequent in California. The research predicts climate change will make the events more common in the future.
The new study examined weather conditions that led to a 2006 heat wave in the southwestern United States.
Temperature records were broken in many locations.
Unusually high humidity levels led to the deaths of more than 600 people, 25,000 cows and 70,000 chickens in California.
Researchers at the Scripps Institution of Oceanography says the 2006 pattern of extreme, muggy heat is part of a trend.
UCSD climate scientist Alexander Gershunov says humid nighttime heat wave events are becoming more common in California.
He says the nighttime heat waves prevent the typical cooling.
Gershunov says the trend towards more frequent and larger-scale muggy heat waves is expected to continue in the region as climate changes over the next few decades.