CLEARWATER — It was so cold at Illinois State University, Jillian Kozlowksi and her sorority sisters had to stay inside or risk getting frostbite.

It was the second "cold day" that did it. When temperatures so frigid canceled classes yet again, Kozlowski made it official: She and her friends would be going to Florida the next month for spring break. They decided on Clearwater Beach after finding a deal on a hotel within walking distance from the lush white-sand beaches.

"It doesn't even have to be a whole week," said Koslowski, 20, as she was sprawled out in a blue lounge chair at the beach. "We knew even a couple days in the sun would be good for us."

They were smart to plan their cold escape even just a month ago, keeping their travel expenses below $400 each. Flights from Chicago to Tampa toward the end of the month, another popular spring break week, are already nearly $1,000 for round-trips through Southwest and Delta airlines. Several flights from the north and Midwest to Florida are already sold out.

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"It sounds cruel," said Visit St. Pete/Clearwater spokesman Leroy Bridges, "but harsh and long winters are great for us. It gives people a reason to head south."

March and the roughly six-week spring break season are always strong for Tampa Bay's tourism industry. But Bridges said analysts' reports paired with what he's seen at the beaches could make this March the first time the county collects $10 million in bed taxes over any month.

The county tourism agency uses the 6 percent tax charged on overnight stays as a metric to measure how the local tourism industry is performing. Last year, Pinellas County collected about $8.9 million via the tourism tax in March — a 14 percent jump from the year before.

Before 11 a.m. on Tuesday, the public parking lot at Clearwater Marina had a "full" sign posted out front. Cars with plates from places such as Ontario, Maine, Pennsylvania and New Jersey were packed next to each other. Parking attendants watched the lot closely, writing tickets for anyone who overran their meter.

Over the weekend in St. Pete Beach, the lot at the Toasted Monkey beach bar and Howard Johnson Hotel was full around noon. It was packed the weekend before, too, leaving parking down the stretch of Gulf Boulevard scarce.

"(Monday) was especially busy," said Matthew Vario, the bar and grill's owner, "and we expect it to stay that way until Easter."

Vario said beach businesses can use the extra seasonal boost following a sluggish fall. Red Tide swept through Gulf of Mexico waters, killing more than 1,800 tons of fish off of Pinellas County beaches, and turning off tourists for parts of September, October and November.

But fall's troubles aren't on the minds of this season's visitors, a mix of college spring breakers, retirees and families.

Kozlowski and her friends didn't want a stereotypical spring break with just drinking and partying. They opted to go a more relaxing route.

"When we go on SnapChat, literally our entire student body is in Fort Lauderdale," she said.

Another group from North Carolina State University echoed a similar feeling.

"It feels safe here," said student Lauren West, 21, as her friends waited to board the Calypso Queen boat tour. "But it's not just retired people. There's young people, too."

Aboard the Clearwater Ferry, Jordan Ross and his 4-year-old son, Connor, peered out into the water looking for dolphins. For the Canadian family, visiting Tampa Bay is a matter of tradition.

Ross' in-laws spend winters in Largo. He and his wife have been visiting every March for the last six years.

"Really, it's the weather that keeps us coming back," said Ross.

On Tuesday, it was just a few degrees above freezing back in his home of Alberta. When asked if he missed the snow, Connor shook his head vigorously side to side.

"Nuh-uh," he said.

Her prefers sand castles to snow balls.

Contact Sara DiNatale at sdinatale@tampabay.com. Follow @sara_dinatale.