Today is well on its way to become the fifth straight day where the high reaches at least 85 degrees. That hasn't happened since a ten-day streak back on July 2013! Today is also the fifth straight day with above normal temperatures. The first time that has happened in nearly two months.
The reason for the heat is the same as it ever was: high pressure off the coast is pumping humid tropical air our way. For now the high humidity is confined to a shallow layer of air near the ground. As the day heats up that low layer of humid air will mix with drier air above, bringing us mostly sunny skies and a high in the muggy mid 80s.
Thanks to continued southerly winds, that layer of humid air will thicken overnight and into tomorrow. Combine that with an approaching cold front and the air will be ripe for heavy showers and thunderstorms, especially north and west of the city. Saturday's high looks like it will reach the lower 90s before a cold front gets here.
Temperatures are expected to return to seasonable levels after the cold front passes. Sunday should be sunny and mild with a high near 80. Monday looks like it won't be quite that warm and early indications are we could be in for a rainy stretch of weather later next week.