Bay Area’s Indian Summer ~ Drought is still on
Average Bay Area temperatures have been scorching in September, reaching near record breaking temperatures of upper 90’s in many parts of the Bay. This increase in temperatures produces a knee jerk reaction to bump up your irrigation water. On the contrary, as you can see, as we move into fall, our Evapotranspiration rates as a percentage of maximum requirements drop extremely quickly. On average we can water 28% less in September and 51% less in October compared to water requirements in July, when watering requirements were the highest.
Historically, in the Bay Area we have some spikes in the temperature during September and October, a phenomenon known as an Indian Summer. We need to resist the urge bump up the water during Indian Summers. The amount of daylight hours drops off quickly in September and October, and along with the shorter days means less solar radiation. These shorter days are the #1 factor in Evapotranspiration. So instead of bumping up your water percentage, adding start times or extra water days, simply run a valve or two manually here and there and be patient, cooler temperatures are on the horizon. The drought is still on, adhere to your district’s water restrictions.