Ripen avocados at 67˚-70˚F, then store at 40˚–45˚F. Ripening can take from 3 to 10 days depending on the time of the year and whether or not it has been treated with ethylene. (Avocados exposed to ethylene ripen more quickly and can shorten the ripening time to 3 days in late season and 5 days in early season.) If avocados are stored below 40˚F, the skin or pulp turns dark.