Calculate the runtime for your sprinkler zones based on NOAA GFS weather forecast data.
The runtime formula uses variables:
W = watering frequency in days
ET = weekly evapotranspiration in inches for your location
R = weekly total rainfall in inches for your location
Rate = minutes to irrigate 1" of water for your sprinklers
Optional: Enter your own variable values and/or runtime formula below using variables W, ET, R, and Rate. The default values and formula calculate sprinkler runtime for watering every 2 days to replace 75% of rainfall-adjusted weekly ET like so:
(W / 7) * (ET * 0.75 - R) * Rate