LOS ANGELES, July 7 (Xinhua) -- High temperatures are expected to heat up many parts in California this week, prompting calls for residents to stay in the shade and fears that the state's frightening wildfire season could soon worsen.

    Heeding warnings from the U.S. National Weather Service (NWS), California Governor Arnold Schwarzenegger on Monday directed state agencies to implement procedures outlined in the state's plan for excessive heat emergencies.

    Daytime highs are expected to reach 105 degrees Fahrenheit (40.6 degrees Celsius) or higher in many areas over the next three days as a massive high pressure system stalls over the state, weather forecasters said.

    "We are coordinating with state and local agencies to help keep people safe during this excessive heat wave," Schwarzenegger said in a statement. "I urge Californians to take proper health precautions as temperatures rise into the 90s and 100s across the state."

    The National Weather Service has issued an excessive heat watch for Tuesday through Thursday for Los Angeles area mountains, but warned that it could be expanded to the inland valleys as temperatures continue to rise.

    "A strong upper-level high pressure system will build across central California on Tuesday and remain stationary through Thursday," according to an NWS advisory. "During this time there will be the potential for temperatures approaching or reaching record levels."

    A red flag alert for high fire danger has been issued by the National Weather Service and forecasters warned that the combination of high temperatures and humidity could be dangerous.

    Meanwhile, thousands of firefighters Monday continued to battle against more than 300 wildfires still burning across the state.

    About 1,400 fires have been contained since California entered the annual wildfire season early two weeks ago when lightning storms ignited forest fires.