The first Spare the Air Alert of the year also goes into effect Monday, and drivers are being asked to limit the distance they travel.
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"We're expecting the temperatures to increase tomorrow, especially in eastern parts of the Bay Area and there will be light winds as well, which means the vehicle exhaust will be cooked up into smog and there will be unhealthy air at the ground level," says Tina Landis with the Bay Area Air Quality Management District.
Kids we talked with are already noticing the hot weather.
"If you guys are wearing a jacket, take it off because it is hot!" says 6-year-old Zoey Little. Zoey was braving the elements, the 90-degree weather in Pleasanton, when we spoke with her on Sunday.
"We were getting ready to go over here when I got on my seat belt, all the seat belts were burning," says Little.
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Yes it was hot, but even the heat couldn't stop an afternoon birthday party from happening at Bernal Community Park in Pleasanton. It's expected to get even hotter on Memorial Day Monday, with a Heat Advisory going into effect, along with a Spare the Air Alert for smog.
"Well when we first got here it was 82 and then it turned up to be 90! Really? So it's burning up here," said 6-year-old Jasmine Paras.
"When my sister said it was going to be in the 80's today I was just like 'um I'm really not used to it being this hot!'" said Leah Lacayanga.
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But with families together again and the football being thrown, it appears that a few tents is all that was needed to keep this party cool.
"This feels great! We haven't had family around together for over a year and it feels great to have everyone together. We're all vaccinated," says Jeff Paras, who was in the park celebrating his son's 4th birthday.
As for recommendations, the kids we talked with had plenty.
"I drink the water so I stay hydrated and not dehydrated because it's a really hot day. What I really want to do is go home and put the fan on," says Jasmine.
"I'm literally sweating. I hope you guys are wearing sandals because it is hot. I forgot to put on my sandals but I'm wearing boots and it is hot," says Zoey.
The heat advisory expires at 9 p.m. Monday night.