A pattern change occurred this weekend with heat building across the western half of the country, and the sizzling temperatures continue today (Thursday) in the desert areas of the Southwest. Record highs were set in several areas of California and Oregon Sunday to Wednesday and more are likely to fall throughout the West today. The "feels like" temperature (heat index) will rise in the afternoon to more than 110°, increasing the threat for heat related illnesses. High temperatures will climb into the triple digits in many areas. The combination of hot temperatures and increasing humidity will combine to create a situation in which heat illnesses are possible. Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. Take extra precautions, if you work or spend time outside. When possible, reschedule strenuous activities to early morning or evening. Know the signs and symptoms of heat exhaustion and heat stroke. Wear light weight and loose fitting clothing when possible and drink plenty of water. Triple digit readings are likely in the deserts of California, Arizona, and Nevada. Excessive Heat Warnings have already been put in place, including Las Vegas and Phoenix. Here's a look at some good reminders as we heat into summer with numerous days including hot weather in the forecast. https://www.facebook.com/WeatherNation/videos/2305448769709319/ We'll continue to cover this top story all week on WeatherNation. ~Meteorologist Meredith Garofalo