If you're spending the Fourth of July weekend outdoors, be prepared for oppressive heat and humidity. Humidity values are only going up Temperatures will climb into the lower 90s each afternoon through the holiday weekend, but it will feel much hotter as heat index values will range from 100 to 107 degrees. Fourth of July weekend forecast Even though those numbers are expected to stay just below Heat Advisory criteria, the heat can still be dangerous if you're outside for long periods.