There are some locations on the mainland that have Time-of-Use pricing where the peak price is over $0.40/kWh but the off-peak is around $0.20/kWh.
Pedant's FYI -- If you care or are interested in using the terms correctly, watts (W) are a measure of electrical power, it's an instantaneous measure. Watt-hours (Wh) are a volumetric measure of energy, i.e. how much power over how long a time. And kilo- (k) is a prefix meaning 1,000. So, at a V3 supercharger, a Tesla can charge at up to 250 kilowatts (kW) of power. And the battery of a Model 3 may have a total capacity of 75 kilowatt-hours (kWh) of energy.