The best time to visit the Antisana volcano is during the dry season, which typically runs from June to September. During this period, the weather is generally clearer with less rainfall, providing better visibility of the volcano and its surroundings. Additionally, the dry season is also the peak tourist season in Ecuador, so you can expect more favorable travel conditions and the availability of services. However, it's always a good idea to check the local weather conditions and consult with local tour operators for the most up-to-date information before planning your visit.