Spring and fall are ideal for Zion Canyon: the park is not as crowded as during Juli/Aug and from May on the temperatures reach 20 degree C (68 degree F).
Be prepared for a wide range of weather conditions. Temperatures vary with changes in elevation and seasons. Day/night temperatures may differ by over 30 degrees Fahrenheit.
Spring weather is very unpredictable. Stormy, wet days are common, but so is warm, sunny weather.
Precipitation peaks in March and September. Spring wildflowers bloom from April through June, peaking in May.
Summer days are hot around 35-41 degrees C (95-107 degrees F.), but overnight lows are usually comfortable around 18-20 degrees C (65-70 degrees F.) Afternoon thunderstorms are common from mid-July through mid-September.
Storms may produce waterfalls and flash floods.
Fall days are usually clear and mild; nights are often cool. Autumn color displays begin in September in the high country, and in Zion Canyon in early November.
Winters in Zion Canyon are fairly mild. Winter storms bring rain or light snow to Zion Canyon, but heavier snow to the higher elevations. Clear days may become quite warm, reaching 15-16 degree C (60 degrees F.); nights are often in the 20s and 30s. Winter storms can last several days and cause roads to be icy, especially on the east side of Zion. Zion roads are plowed, except the Kolob Terrace Road, which is closed in winter. Be prepared for winter driving conditions from November through March.