(KRON) -- A Red Flag Warning has been issued for parts of several Bay Area counties, according to the National Weather Service. The warning went into effect Friday and will remain in effect until 9 a.m. Saturday. Excessive heat advisory extended for the Bay Area, again The weather service is warning of critically dry fuels, very low relative humidity, and breezy winds. Areas under the warning are as follows: Santa Cruz Mountains Eastern Santa Clara hills East Bay hills Santa Lucia Mountains Los Padres National Forest Mountains of San Benito County and interior Monterey County Pinnacles National Park Graphic: National Weather Service A Red Flag Warning, according to the National Weather Service, means dry and windy conditions will exist, leading to "critical fire weather concerns." The NWS advises not burning outdoors due to weather conditions that will be conducive to rapid fire spread and keeping in touch with officials for up-to-date info regarding need for evacuation plans. The weather service further advises having an emergency contingency plan in case a fire starts near you. The warning comes in the midst of a days-long heat wave that has seen an excessive heat warning for the Bay Area extended through 11 p.m. on Saturday.