In a word, yes, but it depends greatly on the amount of sun, and the length of time that you have available prior to use. Depending on the capacity of your water tank or water bag, it could take as much as ten minutes for the water to warm up to a comfortable temperature. For most people, however, they can be more than satisfied with a short lukewarm shower at the end of the day. However, if you’re the type that needs to have a hot shower at the end of a long hike, the better bet is to use one that provides another heat source other than the sun. These can include showers that are heated by propane or natural gas, or electricity to name a few. While they can be a bit more expensive and cumbersome to use in some cases, their fast heating up times can be a welcomed bonus at the end of the day.