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The park’s own summer line is short: wear sunscreen and dress appropriately. Most trails have little shade. On the hiking page, “appropriate” shows up next to footwear for sand, lava, and uneven rock. We are not inventing a winter average. The park page we checked does not print one.
Summer
July and August frequently top 105°F, on the current conditions page. That page says to avoid harder activity from 11 a.m. to 7 p.m. and to carry 32 ounces of water per person per hour. The September 2026 brochure says 11 a.m. to 6 p.m. instead. Use the conditions page the day you go. Clothing will not replace that water.
Wear a brim that shades your face and neck, a shirt you can keep on in the sun, and shoes with grip that you have already walked in. Sandals are a poor match for lava and the steep sandstone on Petrified Dunes. A light color feels better, but we did not find a park rule that requires one. Bring the sun layer even if the morning in St. George feels mild. The canyon trail is more exposed than the hotel parking lot.
Two items already on our packing list fit this season. These go to the retailer, not to an affiliate tag we invented. We are not repeating prices here.
- Sunday Afternoons Ultra Adventure hat. The brand lists a UPF 50+ brim and neck cape.
- Outdoor Research Astroman Air sun hoodie. The product page mixes UPF 50+ and UPF 30 by color. Read the color you buy. It was out of stock when the packing page was checked on Oct 3, 2026.
Spring and fall
The park calls February through May and September through November the peak season for hiking. That is when most people want to be outside, and it is also when a morning can still be cool and the afternoon hot. Wear a layer you can take off and put in the pack. Keep the sun shirt. Shoes stay the same, because the rock does not get softer in October. September is still monsoon season on the conditions page, typically July through September. A light rain shell is reasonable. We are not claiming the park requires one.
Winter
The park stays open, 6 a.m. to 10 p.m., with no holiday closure on the 2026 brochure. “Open” is not a temperature. Check current conditions the week you travel. Bring a warmer layer than a July shirt, and shoes you trust if the rock is wet. If a storm left ice or mud, pick a short trail or the scenic drive instead of a slickrock scramble. Pioneer Names is the hike the park says has the most shade, which is a summer compliment and a winter reason to notice cold corners.
The full water-and-heat rules are on heat and water. Seasons are on when to go.