LOS ANGELES, CA — It looks like Mother Nature isn't ready to let summer pass without one more good heat wave. The Los Angeles Valleys will cook in triple digit heat this weekend and above-normal temperatures all the way to the coast.

An upper-level high pressure system building off the coast is too blame. The pressure system is weakening onshore flow and an increasingly shallow marine layer, said National Weather Service meteorologist Dave Bruno. The hot temperatures increase the risk of fire danger across the region, too. The high in Downtown L.A. Friday is forecast to be 87 degrees, around 10 degrees higher than Thursday, according to an NWS 7-day forecast. It will rise to 90 Saturday, then begin a slow retreat on Sunday, when it's expected to be 89. By Thursday, the high in Downtown L.A. will be 84.

The warming trend will be more pronounced in the San Fernando Valley. Woodland Hills should reach a high of 98 Friday -- a 6-degree rise over Thursday's highs -- and 103 Saturday before reverting to 98 on Sunday. The Antelope Valley will be in the low 100s from Friday through Sunday, which is not at all unusual for that desert region. Temperatures Friday will be 3-6 degrees higher than normal in the San Fernando Valley, and 8-10 degrees above average on Saturday. Similar conditions are forecast in the Santa Clarita Valley, with a high of 97 expected Friday in Saugus, rising to 101 Saturday. But in spite of the spikes, no heat records are expected, Bruno said