 weather update water to the weather the weekly watering number changes with local weather conditions so in the cooler wetter spring it tends to be lower because less water is lost through evapotranspiration  the combination of water lost from the soil through evaporation and from plants through transpiration weather forecast a series of strong weather systems will bring ample rainfall to the portland metro area over easter weekend and through most of next week this wet and cool weather means that there will be no need to water your lawns or gardens for the next week or so  