DENVER (KDVR) — Spring is not officially over until June 21, but summer’s extreme heat has already arrived and sped up the seasonal snowmelt.

According to the National Weather Service, the recent heatwave has led to a “rapid snowmelt” that’s caused flooding in parts of Colorado’s mountains.

Rocky Mountain National Park announced some closures because of the flooding on Tonahutu Creek and the Colorado River. The park said the closures include North Inlet access road, East Inlet Trail, Bowen Gulch access road and Holzwarth Historic site at the access bridge.

A flood advisory was in effect until 6:30 a.m. Wednesday for flooding around the Colorado River above Grand Lake, the NWS said. Minor lowland and meadow flooding will impact nearby trails.

The Poudre River was also seeing high flow, as is usual for this time of year, because of snowmelt. The ice-cold water contains a “great deal of debris,” the Poudre Fire Authority said. The Cameron Peak Fire burn scar has also led to an increase in debris pileups.

“The Poudre River is not safe for novice recreation right now,” the fire authority warned the public. People are urged to wait until later in the season to float the river.

“Typically late July is when we start to see safer conditions. Even then, please wear a personal flotation device,” fire officials said.

Around Boulder Creek, recreators were urged to use caution as snowmelt, along with the annual release at the Barker Reservoir dam, were elevating the creek’s flow.