When is it best to run the lawn sprinkler system: AM or PM? And why?

Question

I live in a city where humidity is high and the summers are very hot. Are these factors to consider? I see my neighbors lawns being sprinklered at different times throughout the day.

Answer 1

Definately water in early morning around daybreak or shortly thereafter.  Leaves left wet are subject to fungal diseases.  Watering early allows them to dry before the heat of the day.  Also watering later wastes near 50% due to evaporation.

Answer 2

I hear that running it at night is more conservative

Answer 3

The optimum time for watering anything is 4-8AM.

Reason being: midday watering is lost to evaporation from the heat and sun and evening watering leaves the lawn ( or plant ) wet overnight which encourages fungal diseases.  

Early morning watering allows the lawn to soak up the water and be not become heat stressed later in the day.

Answer 4

jupiter is completely correct  , but some cities and states for that matter are in a state of drought so check with you local water authority to make sure you are not going to get a fine for watering,

Answer 5

I live in Arkansas where the summers are hot and very humid and a city here passed a law that the sprinklers could only be ran in the late afternoon or early evening.....it makes since because it saves energy, I mean its cooler even if its slightly and it takes less if thats how the sprinklers work.

Answer 6

The best time to water is in the morning, early so that it gives the grass time to dry.