PORTLAND, Ore. (AP) — Some voters living in areas that recently experienced rainy or humid weather have reported receiving ballot return envelopes that are already sealed shut because of moisture dampening mail, elections officials say.

The issue has been reported in parts of North Carolina, where Hurricane Helene brought heavy rains and catastrophic flooding, as well as Pennsylvania, Alabama and Oregon. Elections officials say it’s not the first time this has happened and that humidity has sealed return envelopes in the past.

The elections office in Oregon’s Clackamas County, home to part of Portland and its metropolitan area, said it has received four reports of self-sealed envelopes — out of more than 320,000 ballots that it sent to voters in the mail.

Clackamas County Clerk Catherine McMullen said it happens in every election to some degree, depending on the weather, in counties across Oregon. Her office typically receives a few calls about the issue every election, she said.

“As with any self-sealing envelope, when it gets wet it can self-seal,” she said in an email Thursday.

Elsewhere, Trey Forrest, the absentee election coordinator in Alabama’s Jefferson County, home to Birmingham, said Thursday that some ballots mailed in mid-September were affected by the issue, but that the problem hasn’t come up in the past three or four weeks. Earlier this month, the Pennsylvania Department of State said on the social platform X that humidity was prompting similar concerns.

Voters who have received sealed return envelopes should contact their county elections office to confirm what their next steps should be, as rules can vary across counties and states.