Free Writing Prospectus (Form FWP)

Filed Pursuant to Rule 433

Registration No. 333-276909

Dated October 27, 2025

PRICING TERM SHEET

October 27, 2025

Southwest Airlines Co.

$750,000,000 4.375% Notes due 2028

$750,000,000 5.250% Notes due 2035

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*Note: A securities rating is not a recommendation to buy, sell or hold securities and may be subject to revision or withdrawal at any time.

The information herein supplements the preliminary prospectus supplement and supersedes the information in the preliminary prospectus supplement to the extent inconsistent with the information in the preliminary prospectus supplement.

The issuer expects to deliver Notes against payment for the Notes on the Settlement Date, which will be the fifth business day following the date of the pricing of the Notes. Under Rule 15c6-1 of the Securities Exchange Act of 1934, as amended, trades in the secondary market generally are required to settle in one business day, unless the parties to a trade expressly agree otherwise. Accordingly, purchasers who wish to trade Notes prior to the first business day before the settlement date will be required, by virtue of the fact that the Notes initially will settle in T+5, to specify alternative settlement arrangements to prevent a failed settlement.

The issuer has filed a registration statement (including a preliminary prospectus supplement) with the Securities and Exchange Commission (the "SEC") for the offering to which this communication relates. Before you invest, you should read the preliminary prospectus supplement included in that registration statement and other documents the issuer has filed with the SEC for more complete information about the issuer and this offering. You may get these documents for free by visiting EDGAR on the SEC Website at www.sec.gov. Alternatively, the issuer, any underwriter or any dealer participating in the offering will arrange to send you the prospectus if you request it by calling BofA Securities, Inc. at 1-800-294-1322, Citigroup Global Markets Inc. at 1-800-831-9146, Goldman Sachs & Co. LLC at 1-866-471-2526, J.P. Morgan Securities LLC at 1-212-834-4533 or Morgan Stanley & Co. LLC at 1-866-718-1649.

The communication of this term sheet and any other document or materials relating to the issue of the Notes is not being made, and this term sheet and such other documents and/or materials have not been approved, by an authorized person for the purposes of section 21 of the United Kingdom's Financial Services and Markets Act 2000, as amended (the "FSMA").

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Accordingly, this term sheet and such other documents and/or materials are not being distributed to, and must not be passed on to, the general public in the United Kingdom. This term sheet and such other documents and/or materials are for distribution only to persons who (i) have professional experience in matters relating to investments and who fall within the definition of investment professionals (as defined in Article 19(5) of the Financial Services and Markets Act 2000 (Financial Promotion) Order 2005, as amended (the "Financial Promotion Order")), (ii) fall within Article 49(2)(a) to (d) of the Financial Promotion Order, (iii) are outside the United Kingdom, or (iv) are other persons to whom it may otherwise lawfully be communicated or distributed under the Financial Promotion Order (all such persons together being referred to as "relevant persons"). This term sheet and any such other documents and/or materials are directed only at relevant persons and must not be acted on or relied on by persons who are not relevant persons. Any investment or investment activity to which this term sheet and any such other documents and/or materials relate will be engaged in only with relevant persons. Any person in the United Kingdom that is not a relevant person should not act or rely on this term sheet or any other documents and/or materials relating to the issue of the Notes or any of their contents

No PRIIPs or UK PRIIPs KID - No PRIIPs or UK PRIIPs key information document (KID) has been prepared as not available to retail investors in the European Economic Area or United Kingdom.

Any disclaimer or other notice that may appear below is not applicable to this communication and should be disregarded. Such disclaimer or notice was automatically generated as a result of this communication being sent by Bloomberg or another electronic communication system.

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