Average retail gasoline prices in Maine fell 4.3 cents a gallon last week and stood Sunday at $2.11 a gallon, according to GasBuddy’s daily survey of 1,228 gas outlets in Maine.

Nationally, prices fell 2.3 cents and were averaging $2.02 a gallon, the price-tracking website reported.

Average prices are $1.37 lower now than a year ago at this time, and GasBuddy expects the national average to fall below $2 a gallon this week.

But the long and deep decline is set to bottom out, the website says, and prices may edge up soon. That’s because refineries are processing less crude oil and are preparing for seasonal maintenance, along with the switch to cleaner-burning, summer gasoline blends.

“Last year’s lift began the second week of February and saw the upward trend last until the beginning of May,” said Patrick DeHaan, senior petroleum analyst with GasBuddy.

Diesel prices dropped an average 7 cents per gallon in the last week to $2.83 a gallon.

“By the start of February, diesel will fall under $2.80 a gallon, and by Valentines Day, they’ll fall to $2.65,” DeHaan predicted.