Florida Power & Light customers can expect a slight drop in their monthly electric bills next year thanks to lower fuel costs.

FPL raised prices by 8 percent in August and had projected another 7 percent increase in January. But a dramatic drop in oil and natural gas prices enabled the company Monday to reduce by $975 million its $7 billion in projected fuel and purchased power costs next year.

The revision combined with increases in nuclear expansion costs and other fees would decrease monthly residential bills by 1.4 percent, from $111.12 to $109.55 starting Jan. 6 for the first 1,000 kilowatt-hours of power, slightly less than the average residential customer uses. Residential bills would have jumped to $118.99 under FPL’s previous proposal.

The fuel-cost recovery fee included in that monthly bill would drop 9 percent from $60.21 now to $54.92 in January.

“Natural gas and oil prices came down significantly and we’re happy to pass” the savings to customers, said FPL President Armando Olivera, adding that the “remarkable” volatility of fuel prices also means that “we can’t guarantee these prices stay firm for the duration of 2009.”

The Florida Public Service Commission will consider FPL’s new fuel fee proposal on Dec. 2.

The state’s largest power company also told the commission Monday that it plans to formally propose its 2010 base electric rates in March. The current rate took effect in 2006 and expires at the end of 2009. If fuel prices stay low, FPL predicts that its base rates would increase typical monthly residential bills to between $115 and $118.

Base rates cover general costs of doing business, including operating and maintenance costs for equipment. About one-third of an FPL residential customer bill is the base rate, more than half is fuel costs and the rest is other costs, such as purchased power and environmental and conservation programs.

Utilities in Florida aren’t allowed to earn a profit on the fuel fee but can on other fees, such as the conservation and environmental surcharges.

Earlier this month, groups that represent FPL customers grilled the utility about its fuel costs because the price of oil had dropped by about 50 percent since early August when the utility initially projected fuel costs.

“ It’s good that FPL recognized the somewhat obvious falling price of fuel,’’ said Mike Twomey, an attorney for AARP, a national advocacy group for seniors. “This is an important victory for FPL’s customers and it’s good FPL stepped up to the plate and made the change.”

FPL adjusts the fuel fee when it detects a shift in fuel cost projections of more than 10 percent, which hadn’t happened until recently, Olivera said.

“ It’s easy to look back now” and see the declining trend, he said.