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During spring and fall, the daytime highs average 60° to 80° F and lows average 20° to 50° F. Crowds are largest and campsites and backcountry permits are most difficult to obtain during holiday weekends such as Easter and spring break.
Summer temperatures approach 100° F, and discourage crowds and tend to make strenuous exercise difficult. Most precipitation falls in late summer and early autumn thunderstorms. Winters are cold, with highs averaging 30° to 50° F, and lows averaging 0° to 20° F. Though large snowfalls are uncommon in the park, even small amounts of snow or ice can make trails and roads impassible. Many four-wheel-drive roads are closed in winter.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual | |
| High - °F | 39.0 | 46.0 | 55.0 | 64.0 | 73.0 | 87.0 | 92.0 | 90.0 | 82.0 | 68.0 | 51.0 | 38.0 | 65.4 |
| Low - °F | 19.0 | 23.0 | 30.0 | 34.0 | 46.0 | 58.0 | 62.0 | 60.0 | 51.0 | 40.0 | 29.0 | 22.0 | 39.5 |
| Extreme High - °F | 67.0 | 75.0 | 85.0 | 91.0 | 101.0 | 109.0 | 111.0 | 108.0 | 108.0 | 94.0 | 80.0 | 68.0 | 91.4 |
| Extreme Low - °F | -28.0 | -21.0 | 7.0 | 16.0 | 23.0 | 32.0 | 38.0 | 36.0 | 28.0 | -6.0 | -8.0 | -15.0 | 8.5 |
| Days > 90°F | 0 | 0 | 0 | 0 | 6 | 20 | 30 | 26 | 12 | 0 | 0 | 0 | 88 |
| Days < 32° | 30 | 22 | 17 | 6 | 0 | 0 | 0 | 0 | 0 | 5 | 20 | 29 | 129 |
| Rain - in | 0.63 | 0.29 | 1.07 | 0.76 | 0.71 | 0.50 | 1.15 | 0.92 | 0.69 | 1.00 | 0.86 | 0.60 | 9.18 |
| Snow - in | 5.5 | 1.2 | 2.8 | 3.4 | 0.2 | 0.0 | 0.0 | 0.0 | 0.0 | 0.5 | 3.3 | 2.4 | 19.3 |
| Poss Sun % | 56 | 64 | 60 | 68 | 74 | 83 | 77 | 79 | 80 | 75 | 63 | 60 | 70 |
| Thunderstorms | 0 | 0 | 1 | 1 | 4 | 4 | 9 | 11 | 5 | 2 | 0 | 0 | 37 |

