Temperatures in valley and mountain areas of the Southland again will reach dangerous "excessive heat'' levels today, fall marginally during the week, and rise anew next weekend, according to the National Weather Service.
In Altadena, highs will hover in the triple digits, thanks to a hot air mass resulting from a ridge of high pressure over the Southwestern United States. High humidity levels will make it feel even hotter, according to the weather service.
"The combination of very hot temperatures and moderate humidity will combine to create a dangerous situation in which heat illnesses are possible,'' it said.
Though Altadena can look forward this week to daytime temps of around 100 degrees, nights will cool down to the upper 60's, starting tomorrow.
The weather service urges area residents to take precautions to avoid heat-related illnesses, including: schedule any outdoor work for early morning or evening; wear light, loose-fitting clothing; and drink plenty of water.
Anyone overcome by the heat should be moved into the shade, and 911 should be called.
Maximum temperatures will remain above normal and further warming is now forecast for next weekend.