Can spray foam be sprayed outside?

Yes, with limitations. Spray foam left directly exposed to the sun and weather will begin to degrade after about 1 year (1/16th of an inch per year after the first year). Even when the spray foam will be covered after installation there are other concerns to be considered. Spray foam particles are carried by the wind, making it difficult to apply in windy weather. It also creates the possibility for overspray on surrounding vehicles, windows, and other valuable items. Depending on the dampness and humidity caused by weather, it may not be permissible to apply spray foam to any substrate until the conditions are suitable for spraying. Spray foam applied outside will not adhere properly if it is raining or too humid. Spray foam applied inside will not adhere properly if the substrate is damp or has frost.