Medano Creek Month-by-Month in an Average Year
Below are typical creek conditions for each month of an average season. Less or more snowpack will affect the depth and duration of the creek. See also overall conditions to expect at Great Sand Dunes each month of the year.
While April is the second snowiest month of the year on average, there can also be warmer, sunny days that begin to melt the snowpack. Medano Creek usually arrives at the Dunes Parking Area sometime in April, at first just a trickle. By the end of April, it may be a few inches/cm deep with minimal surge flow.
Flow increases through May, and late May is near the peak of Medano Creek's annual flow. While it is still springtime and winds may arise, especially in the afternoon, May temperatures are generally moderate, with highs in the 60s-70s F. However, snow is still possible at this elevation in May! Trees and bushes along the creek leaf out. There are some "no-see-ums" (tiny biting gnats), but mosquitoes are rarely out in May. Late May and early June are the best opportunity to experience ‘surge flow’, where waves flow down across the sand. In average or wetter years, surge flow waves are high enough for children to float down limited distances on flat inflatable toys. Water comes out of the mountains cold, but warms up significantly when the sun shines on it for a few hours as it spreads across the sand. Because of the creek's popularity, late May and early June weekends are extremely crowded, with long lines of traffic, overflowing parking lots, a crowded beach, and full campgrounds. If possible, plan your visit on a weekday this time of year.
June brings warmer temperatures for water play and generally pleasant conditions the first week of June. Late May and early June are the best opportunity to experience "surge flow", where waves flow down across the sand. In average or wetter years, surge flow waves are high enough for children to float down limited distances on flat inflatable toys. As the creek becomes much lower and warmer around mid-June, mosquitoes will emerge in large numbers. Move away from vegetation, to the far side of the creek to avoid the worst of the mosquitoes: they don't like open sand, but prefer to be near shady bushes and trees. By late June, the water level will be fairly low, only 1 or 2 inches (1-5cm) or may even be drying up. Because of the creek's popularity, late May and early June weekends are extremely crowded, with long lines of traffic, overflowing parking lots, a crowded beach, and full campgrounds. If possible, plan your visit on a weekday this time of year.
In July, unless there are significant ongoing rains, the creek will be retreating back toward the mountains and will be dried up at the main visitor area near the Dunes Parking Lot. It may continue to gently flow at 1/2" - 1" (1-2 cm) deep along the eastern edge of the dunefield, near the Castle Creek picnic area. Castle Creek is accessible by high clearance 4WD vehicle on the Medano Pass Primitive Road. Visitors without 4WD may also access the creek in late summer by hiking approximately 3 miles (5 km) up the creekbed from the Dunes Parking Lot, or approximately 0.7 miles (1km) from the Point of No Return parking area. Mosquitoes are typically still present in large numbers due to the low, warm water, but begin to disappear as the water retreats. July is the warmest month at the park, with average highs in the low 80s F.
In August and September, the creek is still completely gone from the main visitor area near the Dunes Parking Lot. If dry conditions continue, it might not even flow near the Castle Creek Picnic Area. Castle Creek is accessible by high clearance 4WD vehicle on the Medano Pass Primitive Road. Visitors without 4WD may also access the creek late summer by hiking approximately 2 miles (3.5 km) up the creekbed from the Dunes Parking Lot, or 0.7 miles (1km) from the Point of No Return parking area. Mosquitoes are gone in late summer and fall.
