Adding to air quality woes in the Santa Clarita Valley this week, the heat wave is on as triple-digit temperatures are expected to add to the discomfort through the weekend.

The National Weather Service forecasts highs Thursday and Friday (the first day of summer) will climb to 107(f), before cooling off to 103(f) Saturday, then 97(f) Sunday afternoon.

The service says a large high presssure system is stoking the heat wave. Only some coastal communities will be spared the inland inferno.

Skies will remain sunny and mostly clear, with relative humidity 15-20 per cent, and wind blowing at 5 mph from the north-northeast, with occasional gusts up to 30 mph.

Sheriff's authorities remind drivers never to leave children or pets in a vehicle unattended, even with the windows cracked, even for 60 seconds. Death may result quickly.