Zion National Park Temporarily Closed. Current Conditions - Zion National Park (U.S. National Park Service) In summer, temperatures in Zion National Park often exceed 100°F/38°C. Zion experiences monsoons from mid-July into September that results in an increased risk of flash floods. Always be aware of the threat of storms and lightning and be prepared for a wide range of weather conditions. Check the weather forecast and know what to expect on the Weather and Climate page, or find out what it looks like now on the park webcam.