Spring (March–May) and autumn (September–November) are the best seasons for canyon hiking in this part of Utah. Temperatures are moderate, the light is extraordinary, and the canyon floors have water. Summer is brutal — daytime temperatures regularly exceed 40°C in the canyon bottom, and flash flood risk is real during the monsoon season (July–September). Winter is cold but clear, and the lack of crowds makes it appealing for the well-prepared; some trails on Cedar Mesa become difficult with snow or ice.
Monument Valley looks extraordinary in every season, but the long shadows of spring and autumn mornings are worth timing a visit around.