Should you keep a Zion Narrows or Angels Landing hike in a flash flood warning?

For the Narrows, the National Park Service ties access directly to weather and river flow, not to whether a visitor already holds a permit or reservation. The park states plainly that the Virgin River Narrows are closed whenever the National Weather Service issues a Flash Flood Warning, and the closure stays in effect for at least two hours after the warning is lifted (https://www.nps.gov/zion/planyourvisit/narrowssafety.htm, https://www.nps.gov/zion/planyourvisit/thenarrows.htm). Flow rate matters too: the bottom-up Narrows closes to all travel once the river tops 150 cubic feet per second, while the top-down route, including overnight trips, closes above 120 cfs (https://www.nps.gov/zion/planyourvisit/conditions.htm, https://www.nps.gov/zion/planyourvisit/virgin-river-narrows-information.htm). For overnight top-down trips specifically, the park is explicit that wilderness permits are not issued during these closures (https://www.nps.gov/zion/planyourvisit/virgin-river-narrows-information.htm).

The park's own safety guidance is to stay out, not push ahead: it tells hikers that before starting any trip into a narrow canyon they should check conditions and forecasts, and that if bad weather threatens the area they should not enter narrow canyons at all (https://www.nps.gov/zion/planyourvisit/narrowssafety.htm). If already inside and conditions deteriorate, such as darkening clouds, thunder, muddy water, floating debris, or a roar of water upcanyon, the guidance is to seek higher ground immediately and remain there, since water levels usually drop within 24 hours (https://www.nps.gov/zion/planyourvisit/narrowssafety.htm).

Angels Landing does not have the same river-flow trigger, but the permit itself carries no weather guarantee. Recreation.gov states that a permit is an opportunity, not a guarantee that conditions will allow a hike on the scheduled date and time, and that environmental or trail conditions may lead the NPS to close the trail (https://www.recreation.gov/permits/4675310). The park's own page for the hike also tells permit holders to be mindful of conditions and to use caution on the chains, which become slick and more hazardous when wet (https://www.nps.gov/zion/planyourvisit/angels-landing-hiking-permits.htm).

In short, holding a permit for either hike does not override park closures or weather risk. During an active Flash Flood Warning, the Narrows is closed by rule, and Angels Landing can be closed at the park's discretion for environmental or trail conditions. The safe approach on either trail is to check current conditions before heading out and to turn back or wait out high ground if warning signs appear on the trail.