In addition to covering firefighters' families, OPM also said it will allow other agencies to request coverage for temporary workers who are "similarly situated to firefighting personnel."
OPM did not immediately respond to questions about how many other workers might qualify.
"OPM intends to construe this subsection narrowly, applying it only to employees who are engaged in emergency response services similar to the services being performed by those responding to the wildfires, and only when requested by their employing agencies," the regulation states.
The new rules will take effect immediately.
Firefighters will be able to enroll in the Federal Employees Health Benefits Program (FEHBP), the system through which federal workers choose from several private insurance plans.
Seasonal employees, including firefighters, have not been able to use the FEHBP because federal law requires one year of continuous employment. Firefighters "are not eligible for coverage under the FEHBP program at all," OPM stated.
The agency said it has broad regulatory authority that allows it to make an exception.