During spring and fall we may heat the spa, but when the outside temperatures here in the Sonoran Desert climb above 100 or so, the heater goes off and we use the spa as a place to cool off. The water temperature (measured today) was a cool 85° while the ambient temperature on the patio where the tub lives was 104°.
I captioned this photo on the FecesBook™ post I made today as “When it’s a dry heat – get wet!” Click on the image to enlarge (credit to Verna).