Summer has arrived earlier than expected, causing some to wonder how long it will last.

The warm weather, which has brought shorts, T-shirts and sunglasses back into fashion, is a sharp contrast to the frigid temperatures of just a couple of weeks ago.

The sudden switch in temperatures was caused by a change in the jet stream, said Tim Bernas, meteorology major and an employee at the NIU Weather Service.

“The uppper-level winds brought this warm weather up from the southern states,” he said.

“Temperatures will be decreasing somewhat by this weekend—we will probably see highs in the 60s to 70s beginning Saturday,” Bernas said. “This week’s highs will be the warmest for now.”

Temperatures this week ranged from an 81-degree high on Monday to Wednesday’s high of 86, Bernas said.

This week’s temperatures are part of a nation-wide record-breaking trend.

He said this week’s warm weather is no indication as to what this summer’s weather will be like. “It could be warmer this summer, I can’t really say,” Bernas said.

“It’s safe to say we won’t be having any more snow, although last year it did snow in early May,” he said. “This year it seems the weather did change quite drastically compared to last year’s gradual change.”

The warm weather also prompted NIU officials to turn on air conditioning systems in classroom buildings Monday. However, because of the units’ sizes, the buildings have not fully cooled down.