The sun has not risen above the North Pole since mid-September. The sea ice—flat, landlike, windswept, and stretching as far as the eye can see—has been bathed in darkness for months.

But later this week, something extraordinary will happen: Air temperatures at the Earth’s most northernly region, in the middle of winter, will rise above freezing for only the second time on record.

On Wednesday, the same storm system that last week spun up deadly tornadoes in the American southeast will burst into the far north, centering over Iceland. It will bring strong winds and pressure as low as is typically seen during hurricanes.

That low pressure will suck air out of the planet’s middle latitudes and send it rushing to the Arctic. And so on Wednesday, the North Pole will likely see temperatures of about 35 degrees Fahrenheit, or 2 degrees Celsius. That’s 50 degrees hotter than average: It’s usually 20 degrees Fahrenheit below zero there at this time of year.

Winter temperatures have only snuck above freezing at the North Pole once before. Eric Holthaus, Slate’s meterologist, could not find an Arctic expert who had witnessed above-freezing temperatures at the pole between December and early April.