HOUSTON (AP) – Houston airports still expect to stay open after Hurricane Harvey hits South Texas, but airlines are encouraging customers to change travel plans.

United, Southwest and American offered waivers for customers scheduled to fly to, from or through Houston and several other Texas cities from Friday through Sunday. Delta’s waiver of additional charges for changing plans runs through Saturday.

READ MORE: Texas Experiencing Another COVID-19 Surge

Airlines routinely cancel flights when bad weather is expected, although only a few have been scrapped so far, according to tracking service FlightAware.com.

READ MORE: Administrative Court Judge Orders Mask-Wearing To Enter Dallas County Courthouses

Bill Begley, a spokesman for Bush Intercontinental and Hobby airports, says crews are clearing debris from drains and checking pump stations to prevent flooding.

Begley says the airports plan to stay open, but that could change based on what they hear from the airlines and federal aviation officials.

MORE NEWS: Summer Break Ends Early For Some Dallas ISD Schools

(© Copyright 2017 The Associated Press. All Rights Reserved. This material may not be published, broadcast, rewritten or redistributed.)