The Home Depot Inc. prides itself in tying together its online and offline stores to make shopping easy and efficient for its customers. Two major hurricanes within a three-week span, however, can force a change of plans.

Chief financial officer Carol Tome told analysts on the retail chain’s Q2 2017 earnings call in August that more than 43% of the retailer’s online orders are picked up in one of its store locations. While omnichannel has been a cornerstone of Home Depot’s online sales success in recent years, when a major storm such as Hurricane Irma comes bearing down on an area, the retailer’s strategy changes.

In the days leading up to Hurricane Irma, the retailer, No. 8 in the Internet 2017 Retailer Top 500, stopped its buy online, pick up in store service at stores located in Irma’s path and likely to experience high demand for disaster preparedness supplies, a spokesman told Internet Retailer on Tuesday. Irma struck Florida on Sunday, first in the Keys first and then again near Marco Island on the Gulf Coast, before moving inland and through the Southeast as a tropical storm.

Home Depot suspended buy online, pick up in store in part because most consumers went directly to stores to buy goods needed to brace their homes for the storm, the spokesman says. The retailer also did not want to disappoint online shoppers as inventory dwindled .

“Inventory in these emergency situations moves so fast that you can’t have a customer walk in and see a stack of generators in the buy online, pick up in store sections that they can’t buy and that they desperately need,” he says. “We say it’s probably not a bad idea to turn off [buy online, pick up in store] in certain locations. The worst thing we can do is have somebody order something that we can’t fulfill.”

Home Depot was named the Omnichannel Retailer of the Year at the 2017 Internet Retailer Excellence Awards earlier this year.

Both Home Depot and competitor Lowe’s Cos. Inc. (No. 25) have hurricane preparation sections on their respective websites where online shoppers can peruse products they may need before, during and after a hurricane.

Lowe’s activated its Emergency Command Center in Wilkesboro, N.C., ahead of Hurricanes Irma and Harvey, which struck the southeast coast of Texas on Aug. 25. The Command Center, which opened in 1989, helps Lowe’s determine which additional products to send to its distribution centers and stores so that shoppers and relief workers are able to get what they need quickly. Neither Home Depot nor Lowe’s commented on spikes or declines in online sales during the storms.

Planalytics Inc., a firm that tracks the weather’s impact on retail transactions and store traffic, upped its estimate of Irma’s overall impact on lost online and offline retail sales to $2.75 billion over the weekend, a figure the company says it doesn’t expect to increase.

“65% of the state of Florida was without power at some point during the storm so even if they couldn’t get to the store, they couldn’t get online,” says Evan Gold, executive vice president of global services at Planalytics. “That’s going to put a dent into e-commerce sales as well. The near-term impact as things get back online is people will go out and buy things, but most of that is going to be need-based. Need right now is health and property.”

Meanwhile, Irma continues to wreak havoc on package deliveries throughout the Southeastern United States. United Parcel Service Inc. reported on its website that it had suspended package deliveries and pickups to more than 650 ZIP codes throughout Florida (375), Georgia (248) and South Carolina (39). UPS states on its website that it has contingency plans in place and is working to get packages delivered to the affected ZIP codes as soon as possible. UPS is the primary shipping carrier for 421 retailers in the Internet Retailer 2017 Top 1000.

Competitor FedEx Corp. has similarly suspended service to more than 1,000 ZIP codes across Alabama, Florida, Georgia and South Carolina due to damage caused by Irma. FedEx is the main carrier for 318 Top 1000 retailers.

The U.S. Postal Service, carrier to 312 retailers in the Top 1000, says on its site that its Gulf Atlantic District, which includes portions of northern Florida and southern Georgia, “continues to temporarily adjust operations due to recent impacts of Hurricane Irma. Customers are advised that normal service operations in the path of the storm have been interrupted by unsafe conditions such as high winds, flooding or impassable roads.” Retail and delivery service has been suspended until further notice in hundreds of ZIP codes in Florida, Georgia and South Carolina, USPS says on its service disruption alerts page.