Spring has sprung, technically speaking. But Harvard experts say weather in the region will remain unpredictable.

While March 20 marked the first official day of spring, the weather told quite a different story. Temperatures dipped below freezing to 22 degrees Fahrenheit at Logan Airport Monday and 28 degrees last night.

According to Rotch Professor of Atmospheric and Environmental Science Steven C. Wofsy, the scientific explanation for erratic local weather is that “Boston sits on the boundary between a continental and a maritime climate.”

The jet stream is a rapidly moving body of air in the upper atmosphere, and it generally moves from west to east. But, Wofsy said, it also “wiggles.”

Boston’s momentary position relative to the jet stream can wreak havoc on weather forecasts. “Variability of a few hundred miles can make the difference between a storm bringing rain to a region and a storm bringing snow,” said Brian F. Farrell, the Burden professor of meteorology.

That makes long-term forecasting particularly tricky. “You can’t predict more than a week or two at a time,” Farrell said.

According to Farrell, the jet stream “wanders on week-long, or monthly time scales.” This mercurial pattern leads to stretches of unusual warmth as well as unseasonably cold spells in Boston, Farrell said.

As Wofsy put it, Boston is particularly likely to experience a “January thaw” as well as a “January freeze.”

And March, likewise, can either go out like a lion or a lamb.

According to Weather.com, temperatures in Boston on today’s date, March 22, have ranged from a low of 11 degrees—registered in 1934—to a high of 72 degrees in 1948.

So what sort of weather do Harvard experts predict for the coming weeks?

“Chaotic,” said Farrell.

“Variable,” said Wofsy, “although as we move towards summer, it will obviously get warmer,” he added.

Student reactions to Boston’s wacky weather are as disparate as the region’s temperatures. “It was cruel to have that 65-degree day and now be back to sub-freezing temperatures,” said Michael F. Esposito ’09. But Sergio Prado ‘09 remarked that the variability “keeps things interesting.”