Temperatures are expected to rise throughout the weekend and break the 90-degree mark along the way, according to the National Weather Service in Hanford.
Meteorologist Cindy Bean said a strong ridge of high pressure has moved over the region, bringing warmer temperatures and drier conditions. On Friday, she said the temperature hit 84 in Merced, a jump of 5 degrees from Thursday.
Bean is expecting the high today to hit 89 degrees and rise to 91 by Sunday. She said the temperature should rise slightly on Monday and then back off a little Tuesday before heading back up.
Bean said the ridge of high pressure "is in control right now. It will keep us warm and dry."
While there aren't any triple digits in the forecast yet, Bean said summer is just around the corner and so is the extreme valley heat it brings.
The warm temperatures this weekend are likely to bring out lots of folks for a variety of activities, from the MiddleState Independent Comedy Film Festival and comic Adam Carolla's show to the Love Merced community cleanup and American Cancer Society's Relay for Life all in Merced.
Saturday also marks the opening of trout season for most of the state. There are guided nature hikes at Pacheco State Park and the waterfalls at Yosemite National Park are running strong.
But the weather service is warning the public to use caution near river and lakes, Bean said.
Although they will appear inviting because of the warm temperatures expected this weekend, the weather service says the risk of hypothermia is high.
"People in or near area lakes, rivers and streams should remain cautious to the dangers of cold springtime waters," according to the weather service website. "If exposed to cold waters, even experienced swimmers can lose muscle control very quickly and fast flowing water will make rescue difficult."
Hypothermia is caused by a sudden loss of body temperature and can be fatal. Symptoms include shivering, cold hands and feet, numbness, loss of dexterity, mental sluggishness and cold-triggered pain.
Anyone exhibiting those symptoms should get help immediately, the weather service advises.