In the beginning of the movie when Brick Tamland is giving the weather report, it says that it is 82 degree's in San Diego. Well, throughout the rest of the movie, the temperatures on the WHOLE board never change. I'm sure it isn't the same temperature for 3 weeks.
Actually, the greatest thing about being a weatherman in California besides the huge salary, is that the weather can be very predictable and doesn't change that much from day to day...so it might have been.