NPS/Patrick Myers JanuaryJanuary is usually the coldest month of the year, with average highs only in the teens to low thirties F and lows in the single digits to below zero F. Snow and blizzards are possible, though most days are sunny and calm. Roads are usually quickly cleared of snow. Snow falls on the dunes about once per week, but it typically melts off within a few days. Mountain hiking trails are under deep snow, but foothills trails may be packed down or have shallow snow. High-clearance 4WD vehicles can usually make it to Castle Creek Picnic Area along the Medano Pass Primitive Road, but the remainder of the road is closed for the winter season beyond that point. During this quiet season, elk and pronghorn are often seen in early morning or evening hours in the grasslands. 
NPS/Patrick Myers FebruaryFebruary has somewhat warmer temperatures than January, with average highs around 39 F and lows averaging 14 F. Snow and blizzards are possible, though most days are sunny and calm. Roads are usually cleared quickly of snow. Snow falls on the dunes about once per week, but it typically melts off within a day. Mountain hiking trails are under deep snow, but foothillls trails may be packed down or have shallow snow. High-clearance 4WD vehicles can usually make it to Castle Creek Picnic Area along the Medano Pass Primitive Road, but the remainder of the road is closed for the winter season beyond that point. During this quiet season, elk and pronghorn are often seen in early morning or evening hours in the grasslands. 
NPS/Patrick Myers MarchPlan on volatile weather in March. Some March mornings are sunny and calm, but most afternoons have high winds. Plan to experience the dunes in the morning if possible. Be prepared for occasional blizzard conditions and deep snow as well: March is the snowiest month of the year on average. Average highs are around 47 F and lows average 21 F. However, during winter storms temperatures may drop into the single digits, or in later March may reach a calm, sunny 60 degrees. Roads are usually cleared quickly of snow. Snow falls on the dunes about once per week, but it typically melts off within a day. Mountain hiking trails are under very deep snow, but foothills trails may be packed down or have shallow snow. High-clearance 4WD vehicles can usually make it to Castle Creek Picnic Area along the Medano Pass Primitive Road, but the remainder of the road is still closed for the winter season beyond that point. Elk and pronghorn are sometimes seen in early morning or evening hours in the grasslands, but spring break traffic may move them farther away from roads. Medano Creek is still mostly frozen on the eastern side of the dunes, but will start trickling toward the main Dunes Parking area. 
NPS/Patrick Myers AprilLike March, April has volatile weather and often blustery conditions. Though the dunes don't get too hot on April afternoons, wind is common. Plan to experience the dunes in the morning to avoid the highest winds. April is the second snowiest month of the year on average. Typical highs are around 56 F and lows average 28 F. Roads are usually cleared quickly of snow. Snow falls on the dunes about once per week, but it typically melts off within a day. Mountain hiking trails are under very deep snow, but lower sections are melting out or dry. High-clearance 4WD vehicles can usually make it to Castle Creek Picnic Area along the Medano Pass Primitive Road. The remainder of the road may still be still closed for the winter season beyond that point, unless dry conditions permit opening it farther into the mountains. Elk and pronghorn are sometimes seen in early morning or evening hours in the grasslands, but increasing traffic may move them farther away from roads. Trees are not yet leafed out. Medano Creek melts and moves father around the dunes, trickling down to the main Dunes Parking Area sometime in April. By late April, it may be up to a few inches deep. 
NPS/Patrick Myers MayLate May is the average 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 in May at this elevation. Trees and bushes along the creek leaf out. There may be 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 up to about 20 inches (50 cm) high flow down across the sand. In wet years with good peak runoff, children can float down the waves on flat inflatable toys. Water comes out of the mountains cold, but warms up significantly when the sun shines on it 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. 
NPS/Patrick Myers JuneJune brings warmer temperatures for Medano Creek water play, with highs averaging 76 F, and lows around 45 F. Flow is at or close to peak in late May and early June. 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. 
NPS/Patrick Myers JulyMedano Creek will begin to retreat back toward the mountains in July, drying up at the main visitor area near the Dunes Parking Lot. It will continue to gently flow (about 1 inch or 2 cm deep) along the eastern edge of the dunefield, near the Castle Creek Picnic Area along Medano Pass Primitive Road. With low water around for breeding, numerous mosquitoes are present from mid-June through July. Afternoon thunderstorms are common in July and August, bringing wind, lightning and potentially heavy rain. They also bring up mountain wildflowers in Great Sand Dunes National Preserve. 
NPS/Patrick Myers AugustAugust is the second warmest month at the park, with average highs in the upper 70s F and lows in the upper 40s F. Sunny, calm conditions generally prevail except during storms. Sand temperatures may still soar to 150 degrees F; always plan your dunes time for early morning or evening to avoid burned feet, heat exhaustion, or fatal lightning strikes. 
NPS/Patrick Myers SeptemberSeptember has some of the best weather of the year, with an average high of 71 F and a low of 42 F. Sunny, calm conditions generally prevail except during storms. The dunes may still get very hot on early September afternoons, with surface temperatures reaching up to 150 degrees F. 
NPS/Patrick Myers OctoberOctober brings chillier temperatures, but there are also some pleasant days, especially in the first half of the month. The average high is 60 F with lows around 32 F. Sunny, calm conditions generally prevail except during storms. The dunes have pleasant temperatures even in afternoon hours. The first snows typically fall on the dunes in late October. 
NPS/Patrick Myers NovemberNovember is early winter at this elevation, with highs averaging 46 F in the day and lows reaching 20 F at night. Winter storms are possible, but most days are sunny and calm, with pleasant afternoon conditions on the dunes. Elk and pronghorn start to be more commonly seen in the grasslands in early morning or evening as the park gets quieter. Visitation drops off considerably, but Thanksgiving weekend can be somewhat busy. 
NPS/Patrick Myers DecemberDecember brings heavier and longer-lasting snow along with much colder temperatures. The average high is 36 F with lows around 11 F, but sub-zero temperatures are possible. Snow falls about once per week on the dunes and mountains. Roads are usually quickly cleared of snow. |
Last updated: March 31, 2020