Markit's reading of new business at service companies in February surged to 56.7 from 51.7 in January, which was the lowest reading in the history of the Markit services sector series dating to October 2009.
"While parts of the East Coast have struggled in the face of adverse weather, other regions basked in unusually warm temperatures, boosting business above seasonal norms," said Chris Williamson, chief economist at Markit in a statement. "Activity levels surged higher and inflows of new business boomed as a result."
Markit last week said its flash U.S. Manufacturing Purchasing Managers Index rose to 54.3 in February, up from January's final reading of 53.9.
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"Alongside the upturn signaled by the sister 'flash' manufacturing PMI survey, the improved performance of the service sector in February means the economy looks to be enjoying yet another spell of robust growth in the first quarter," Williamson said.
The surveys portray U.S. gross domestic product as growing at 3 percent or more on an annualized basis, Williamson said.
The service index's employment component also rose in February and remained above 50, the level which separates expansion from contraction.
Markit's seasonally adjusted flash U.S. Composite PMI Output Index rose to 56.8 in February, its best monthly reading since October, from 54.4 in January.