Turn off the hot tub heater and jets. Unplug the power cord. Disconnect any electrical connections.
Install windbreaks, such as fencing or privacy panels, around the tub to reduce heat loss.
Keep a cover on the hot tub when it's not in use. The cover insulates it and keeps the water cooler. For warmer water, keep the cover off during the day. Sunlight warms the water.
Remove the cover at night to cool the water.
Apply sanitizing chemicals to the hot tub, as directed by the manufacturer, to keep the water clean and clear.