Last update: 5 p.m. ET. Next update: By 11 p.m. ET

Another day, another set of weather-related headaches. That’s how it’s been for air travelers so far in 2015, and that’s how it was again on Wednesday. And how it was already shaping up for Thursday, too.

Nearly 1,500 flights had been canceled nationwide and another 2,225 delayed as of 5 p.m. ET, according to flight-tracking service FlightAware.

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And that was just for Wednesday. More than 660 flights for Thursday had already been preemptively canceled.

All that comes as yet another round of winter weather disrupts flights over large portions of the country. Adding to fliers’ woes, Southwest temporarily grounded 128 Boeing 737s — about one-fifth of its fleet — Tuesday night on concerns about missed inspections. The planes have since been cleared to keep flying, but not before Southwest canceled about 90 flights from Tuesday into Wednesday.

As with previous storms, airlines waived change fees for customers ticketed to fly into airports experiencing poor weather. The policies varied by airline, though they generally allowed customers to make one change without paying the customary change fee.

With the latest cancellations, airlines have now grounded nearly 7,300 flights since Saturday, when the first of the latest set of winter storms began disrupting air travel.

For Wednesday, the worst problems were in Texas and the Southeast, where snow and ice were possible across large parts of the region.

Among the airports affected: Atlanta’s Hartsfield-Jackson International, the world’s busiest airport. More than 550 flights — about 20% of the day’s entire schedule — had been grounded as of 5 p.m. ET.

The airport is the biggest hub for Delta Air Lines and also is a major base for Southwest Airlines.

And at Charlotte — a large hub for American and merger partner US Airways — close to 300 flights had been grounded as of 5 p.m. That accounted for nearly 20% of the day’s schedule, according to FlightAware. Up to six inches of snow was possible there later Wednesday into Thursday.

Charlotte already was seeing cancellations pile up for Thursday, with nearly 300 fights — about 20% of the day’s schedule — already preemptively canceled. A large portion of Thursday’s schedule already was canceled at the Raleigh/Durham and Greensboro airports, as well. Other airports where the Thursday cancellation count was climbing included Greenville/Sparanburg, S.C.; Newport News, Va.; Norfolk, Va.; Richmond, Va.; and Wilmington, N.C.

There also were more cancellations Wednesday at Dallas/Fort Worth, an airport that was both recovering from a storm that ended Tuesday and suffering the effects of a new one that arrived overnight into Wednesday. A mix of rain, sleet and snow was expected to fall there Wednesday morning.

About 250 flights had been canceled there as of 5 p.m. ET, representing more than 10% of the day’s schedule. DFW is the biggest hub for American Airlines.

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