The National Weather Service warned Southern Californians Friday night to beware of "excessive heat."
The Weather Service noted that heat and humidity in San Bernardino and Riverside counties "will push conditions to just below excessive heat warning criteria."
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"An excessive heat warning means that a prolonged period of dangerously hot temperatures will occur. The combination of hot temperatures and high humidity combine to create a dangerous situation in which heat and illnesses are likely," according to the National Weather Service.