With stormy weather in the forecast for Halloween, public officials in Tisbury and Oak Bluffs both announced that trick or treating would be postponed until Saturday.

Tisbury selectmen voted Tuesday to postpone a popular slate of downtown Halloween events, including trick or treating on William street and a Main street puppet parade.

“We’ve got a dark and stormy night [predicted] for Halloween,” said board chairman Melinda Loberg at the regular selectmen’s meeting in the Katharine Cornell Theatre.

The change came at the request of the Tisbury Business Association, which sponsors the parade and other events at downtown businesses.

And Halloween is when throngs of Islanders head for William street Vineyard Haven, a top-ranked neighborhood for trick or treaters on Martha’s Vineyard.

On Wednesday, Oak Bluffs followed suit with an announcement from police that trick or treating would be postponed for safety reasons.

Meanwhile, after hearing some grumbling from Islanders about thee postponements, the Martha’s Vineyard Museum said it would open its doors from 5 to 7 p.m. on Halloween for games and candy.

All are welcome, museum development director Katy Fuller said.

There will be a scavenger hunt for families, candy in every gallery and cider and hot chocolate in the museum cafe.

In an announcement that went out Wednesday, Tisbury selectmen said the following street closures to vehicle traffic will be in effect on Saturday:

• Main street will be closed from 3 to 3:30 p.m. for the parade and trick or treating.

• William street from Spring street to Woodlawn, and Centre street from Main to Franklin will be closed from from 4:30 to 9:30 p.m.

The annual town hall haunted tour has been canceled because it could not be rescheduled, the announcement said.