NORTHWEST NATURAL GAS CO

Director Retirement

The following disclosure is intended to satisfy any obligation to provide disclosures pursuant to Item 5.02(b) of Form 8-K:

On February 25, 2026, Karen Lee notified NW Holdings that she intends to retire from the Board at the end of her current term, which expires following the 2026 Annual Shareholders Meeting scheduled for May 28, 2026. She will additionally retire from the Board of NW Natural at such time.

Ms. Lee has served as a director since 2021. She currently serves as a member of the Finance and Public Affairs and Environmental Policy Committees.

In connection with Ms. Lee’s notice and in accordance with NW Holdings’ Amended and Restated Articles of Incorporation, the Board approved a resolution reducing the number of directors comprising NW Holdings’ Board from 11 to 10 members, effective as of the expiration of Ms. Lee’s term.

Rule 10b5-1 Trading Arrangements

From time to time, our officers (as defined in Rule 16a-1(f) of the Exchange Act) and directors may enter into Rule 10b5-1 or

non-Rule 10b5-1 trading arrangements (as each such term is defined in Item 408 of Regulation S-K). During the three months ended December 31, 2025, none of our officers or directors adopted, modified or terminated any such trading arrangements.