Jan 7 (Reuters) - U.S. Northeast power and natural gas prices for Friday jumped to their highest since January 2018 as homes and businesses crank up their heaters during the region"s first big snow storm. Temperatures in New York City, which received about 4 inches (10 centimeters) of snow in the morning, will reach 35 degrees Fahrenheit (2 degrees Celsius) on Friday, 32 on Saturday and 40 on Sunday, according to AccuWeather. The normal high in New York is 38 degrees at this time of year. Next week, AccuWeather warned highs in New York will only reach 33 F on Monday, 21 F on Tuesday and 28 F on Wednesday before returning to near normal levels later in the week. Since most Northeastern homes and businesses use gas for heat and much of the region"s electricity comes from gas-fired power plants, electric and gas prices usually soar during extremely cold weather. read more Next-day gas prices in New York City and New England jumped to $16.25 and $24.47 per million British thermal units, respectively, their highest since hitting record highs of $140 in New York and $83 in New England in January 2018. Spot power prices in New England also hit their highest since January 2018, reaching $166 per megawatt hour for Friday and around $210 for all of next week. New York and New England do not have enough gas pipeline capacity to supply all the fuel needed for both heat and power generation on the coldest days, so many gas-fired plants switch to more expensive oil and liquefied natural gas (LNG) when temperatures drop. read more So far on Friday, power generators in the region were still getting all the gas they need with grid operators in New York - New York ISO - and New England - ISO New England - saying their systems were operating normally.