Nearly a month after an Arctic blast knocked out more than 18 of 30 Texas refineries, and almost 5 million barrels a day of crude-processing capacity, all but two sites have restarted all or a good portion of the production units they need to make gasoline and diesel again. After a year of slashing production as they lost money because of the pandemic, many refineries may ramp back up hard to catch improved margins and increased demand.

While it’s still more than two months before summer driving season starts, there’s money to be made. A measure of profit margins on making gasoline, diesel and other refined products relative to crude oil, known as the 3-2-1 crack spread, surged above $22 a barrel Friday.

Total SE’s Port Arthur refinery on the Texas Gulf Coast, for one, has nearly completed its restart and may run at full rates by early next week because of market improvements, people familiar with operations said.

About 2.24 million barrels of capacity are back online already, and about another 2.9 million barrels are in the process of restarting.