MOUNT WASHINGTON, New Hampshire (CBS) — Fall may have just officially begun last week, but on Mount Washington, there’s a sign that winter is coming.

The Mount Washington Observatory tweeted a photo Monday morning of rime ice at the mountain’s summit.

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Rime ice is made up of supercooled water droplets that freeze when they come into contact with an object.

When temperatures are below freezing, rime ice can create stunning formations–like these, seen atop Mount Washington last November.

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Rime ice on Mount Washington (Image credit Mount Washington Observatory)

Rime ice on Mount Washington in 2015. (Image credit Mount Washington Observatory)

In a post Sunday night on the Mount Washington Observatory website, Senior Weather Observer and Education Specialist Mike Carmon wrote that the team of scientists at the highest peak in the Northeastern United States was experiencing their first cold snap of the season.

On Monday, the team woke to a light blanket of rime ice.

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The team said their first “shovel-able” snowfall usually doesn’t come until October–last year, it fell on October 18.