street shower by Several seconds on Flickr

Welcome to the coolest day of the week! The wind is coming out of the south today and that will bring enough "cool" air from over the ocean to keep today's high right around 90 degrees. The high humidity, however, will make it feel like the mid 90s. Take advantage of the city's cooling centers if you don't have air conditioning.

The heat is mostly coming from a moist, tropical surface air mass. An upper-level ridge of high pressure is going to pass over that air mass tomorrow and the vertical alignment of the two is a sure bet for unpleasantly hot conditions. Sinking air from the ridge means lots of sun and will suppress any chance that the hot air near the ground will mix with cooler air above. Mid 90s tomorrow, near 100 on Friday and another day at least in the mid 90s is expected on Saturday. Add in the humidity and it will feel several degrees warmer. The air quality isn't going to be all that great either, so take it easy out there!

Relief from the excessive heat will probably arrive sometime on Sunday. An upper-level trough of low pressure is expected to push the ridge southward. Highs Sunday will be in the mid 80s, which is normal for this time of year. Monday should be even cooler with a chance of showers.