The operators of Texas’s electrical grid, as well as state leaders and officials in surrounding states, had ample warning that a winter storm would bring record cold that could cause power demand to spike and threaten electrical infrastructure, according to a review of publicly available data from the National Weather Service.

In fact, forecasters warned of the Arctic outbreak’s severity more than a week in advance, which might have been enough time to take some steps to help mitigate the need to cut power to millions in Texas.

A staff meteorologist at the Electric Reliability Council of Texas (ERCOT), which operates the state’s grid, even sounded the alarm about the cold days before it arrived.

As early as Feb. 5, 10 days before the Arctic air moved into the South, the National Oceanic and Atmospheric Administration (NOAA) highlighted the risk of unusually cold weather and winter storms across the central and southern United States.

Maps produced by NOAA’s Climate Prediction Center showed an 80 percent chance of below-average temperatures from Feb. 11 to 15, from Texas north to the Dakotas, with slightly lower chances of unusual cold stretching from coast to coast.

The agency also forecast a 70 percent likelihood of below-average temperatures from Texas to Indiana during the Feb. 13-19 period, an unusually high level of certainty so far in advance.

These outlooks are used by utilities and financial firms to anticipate changes in prices for fuels used for heating, such as natural gas. At the same time, weather forecasters in the private sector who have clients in the energy industry were also warning of the severity and duration of the upcoming cold.

“We started seeing indications around Feb. 5. Between Tuesday the 9th and Friday the 12th, we knew there were going to be big problems,” said Matt Rogers, president of the Commodity Weather Group, which advises energy companies. “Everyone knew something big was coming, but we weren’t sure what was going to break,” he said, referring to potential issues with infrastructure.

On Feb. 12, the magnitude of the impending cold blast was apparent to ERCOT senior meteorologist Chris Coleman. “This period will go down in Texas weather history as one of the most extreme events to ever impact the state. Temperatures early next week will set widespread daily records that are likely to be the coldest experienced since the 1980s,” Coleman wrote in a blog post on ERCOT’s website.

He continued: “In addition to the extreme temperatures, two major winter storms are projected over the next week. The first will begin on Sunday with near-blizzard conditions in West Texas. The storm will spread eastward Sunday night into Monday, impacting the entire state with widespread snow, sleet, and ice. A second storm appears increasingly strong as it’s set to arrive around next Wednesday with more snow and ice.”

Within NOAA, the Climate Prediction Center also forecast a “high” risk of “hazardous cold” across the central United States, including Oklahoma and Texas, which corresponds with at least a 60 percent likelihood that such low temperatures would occur. The time frame forecasters laid out was Feb. 13 to 19. A subsequent outlook was released Feb. 8, warning of “much below normal temperatures” from Feb. 16 to 19 across the center of the Lower 48 states, including Oklahoma, Texas and Arkansas.

According to National Weather Service spokeswoman Susan Buchanan, the agency’s offices in Texas began sending email briefings on the upcoming cold to partners in the emergency management and government communities on Feb. 8.

The agency’s Weather Prediction Center (WPC) in College Park, Md., included specific language about the cold temperatures in one of its outlooks on Feb. 9, stating, “Arctic air extends across the Northern Rockies and Plains, Surging South across the Plains and MS Valley, with multiple cold temperature records expected.”

On Feb. 11, the WPC specifically warned of temperatures plunging to “at least 30-45F below normal.”

Also Feb. 11, the Weather Service forecast office in Houston published a briefing package stating: “Travel Sunday night through Tuesday will likely be hazardous. Pipes may freeze, burst with damage to infrastructure. Ice accretion, wind and power demand could lead to power outages.”

According to Buchanan, the Texas Division of Emergency Management began holding statewide conference calls about the upcoming winter storm on Feb. 9, and webinars began from some Texas Weather Service offices the same day.

Texas Weather Service forecast offices issued their first winter storm watches on Feb. 11, and eventually, the entire state was placed under a winter storm warning Sunday.

In the end, though, it may not have been possible for the Texas grid to have avoided significant problems during this record-breaking cold snap. ERCOT would not have been able to order utilities to take steps to winterize power equipment across the state in just 10 days.

The lack of winterization had been highlighted in reports on previous outages during cold weather, and the cost of these changes had been a major impediment to following through.

However, with Congress and the state government set to investigate what went wrong, one focus of the inquiry is likely to be on what actions officials did or did not take once they were warned of the weather to come.

Steps could have been taken at the very least to better prepare Texans for the likelihood of lengthy outages and devise plans to avoid a near-total collapse of the entire grid.

Jason Samenow contributed to this article.