The high cost of keeping warm during a bitter cold snap sent fuel heating oil and natural gas to two-year highs yesterday.

Speculators had been driving up wholesale prices of both in the past five weeks following a blizzard on Christmas weekend that crippled the Big Apple and much of the Northeast.

After prices peaked yesterday, many investors began unloading their positions later in the day for quick profits, causing a drop that snapped the speculative rally.

At the same time, investors began placing new bets that prices for both would start skidding, aware that a spring thaw is just two months away and that inventories are still overflowing.

“Heating oil inventories are already 6.35 percent higher than they were a year ago,” said energy analyst Peter Beutel of Cameron Hanover, adding that the oversupply alone could whack prices.

Heating oil slipped 3.15 cents to $2.6193 a gallon here. In earlier trading, the heating oil contract hit $2.6788, its highest level since Oct. 3, 2008, before giving up some of those gains. It’s unlikely that any price drops would be readily passed to consumers.

Natural gas producers also began betting heavily that prices would start dropping due to oversupply and near-record production. Natural gas inventories are 7 percent higher than they were a year earlier, according to the Energy Department.

Natural gas fell from its rally’s peak last week of $4.736 per 1,000 cubic feet, dropping 14.5 cents to $4.598 per 1,000 cubic feet.

Meanwhile, crude oil and wholesale gasoline prices also dipped on oversupply problems, with crude falling to $87.87 a barrel here, off $1.25. Gasoline fell 4.57 cents a gallon to $2.4132.