Natural-gas prices surged to their highest one-day percentage gain in 11 months as weather forecasts showed colder-than-expected temperatures toward the end of January.

Gas has rallied for two days, pushing its strongest day of gains and back-to-back gains, by percentage, since mid-February. Futures are up nearly 16% since Monday’s close.

The move demonstrates how powerful a force winter can still be at boosting the market, analysts and traders said. Record production, tepid demand from a mild December and predictions for a warmer-than-normal late January had led to a massive selloff, dropping prices by more than a third since November. But the late-January forecasts are reversing course, boosting expectations for gas demand to heat homes.

“This should get the market’s attention that there’s still some demand to be dealt with here,” said John Kilduff, founding partner of Again Capital in New York. Late last week he said he was buying futures contracts, predicting that prices would soon surge above $3 a million British thermal units. “The market had just gotten ahead of itself with prices.”

The front-month February contract settled up 29 cents, or 9.9%, at $3.233/mmBtu on the New York Mercantile Exchange. It set a new three-week high closing price and intraday price.