Below are current conditions, weather forecasts for Zion Canyon and towns in the surrounding areas, and water levels for the Virgin River. While these forecasts may be informative, they do not definitely prove whether or not it is safe to hike a canyon on any given day. Your safety is your responsibility; live to hike another day!
When looking at USGS water data, CFS (cubic feet per second) is the important number to look for. Levels below 50 cfs indicate relatively easy hiking conditions in the Zion Narrows. Above 100 cfs, hiking can be difficult or dangerous. The popular Zion Narrows Day Hike (Bottom-Up from the Temple of Sinawava) is closed when flow is above 150 cfs for over 24 hours. The Zion Narrows Top-Down Hike is closed when flow is above 120 cfs. View the full North Fork Virgin River Water Levels USGS page.
SPRINGDALE:
Springdale is at the heart of Zion Canyon and this forecast gives a good sense of conditions in Zion Canyon.
ST. GEORGE:
St. George is located roughly 30 miles west/southwest of Springdale. At a lower altitude than Zion Canyon, St. George is usually hotter.
MT. CARMEL JUNCTION:
Mt. Carmel Junction is roughly 10 miles east of the east border of Zion National Park and the forecast may illude to the conditions in the Upper East Canyon and beyond.
CEDAR CITY:
Cedar City is approximately 20 miles north of the Kolob Section of Zion National Park. At a higher elevation than Zion Canyon, temperatures are usually cooler.
The SNOTEL site is particularly useful during winter and early spring months when attempting to predict how strong and long the spring runoff will be in the Zion Narrows. View the Kolob SNOTEL Site Readings and click on the "View Current" option. The right column will show the remaining snowpack. When the number approaches 0, spring runoff will be over in a few days. Choose "View Historic" to compare snowpack to previous years; as reference, 2005 and 2011 were particularly snowy years and 2002 and 2012 were mostly dry.
40 cfs is close to "normal" for the East Fork in the drier months; levels that are much higher could indicate difficult or dangerous conditions in Parunuweap Canyon. View the full East Fork Virgin River Water Levels USGS page.