More than 250 Cook County corrections officers called in sick Friday morning in a wave of illness jail officials suspect has more to do with the foot of snow covering the Chicago area than an outbreak.

The 258 officers who reported sick amounted to more than a third of the 765 officers scheduled to work the morning shift Friday, said Cara Smith, Sheriff Tom Dart’s chief of policy. Another 158 officers called in sick for the shift that began at 3 p.m.

That amount is the third-highest number of officers to call off sick on a single day since the Super Bowl Sunday in 2015 and that following Monday, Smith said.

“Despite the bad weather, this is a very unfortunate circumstance that puts a tremendous strain on the people who do show up for work as they should,” Smith said.

Chief Judge Timothy Evans announced Thursday afternoon that there would be only bond court at county court buildings, which Smith said lightened the duties of jail guards who otherwise would have had to shuttle prisoners from the jail to court for other hearings.

Dart, for several years, has complained about the suspicious bouts of illness that seem to accompany holidays and major sporting events, Smith said, though the office noted that only 52 officers called off sick for Super Bowl Sunday last week— though 101 officers took sick days on Monday. Under federal law, many officers have requested sick time based on “intermittent” medical conditions, Smith said.

Disproving claims of illness requires time-consuming audits and investigations the office is not equipped to perform on a regular basis, Smith said. Union leaders have said that officers often suffer from injuries stemming from their dangerous workplace and high-stress.

“Certainly, there are people in that group that called in sick who really are sick, or who do have a problem” involving a sick family member, Smith said.

A spokesperson for the Teamsters Local 700, which represents corrections officers, did not immediately respond to requests for comment Friday.