2026 Annual Shareholders Meeting Presentation

Annual Meeting of Shareholders

April 30, 2026

NWE's President & CEO - Brian Bird

Brian Bird

• Current position since January 2023

  • President & Chief Operating Officer 2021-2022

  • Chief Financial Officer 2003-2021

• Board member since January 2023

• 25-plus years energy and utility industry experience

• Serves on Board of Directors for the following organizations: Energy Insurance Mutual, North Central Electric Association (Past President), University of Idaho Utility Executive Course (Former Board Member), Feeding South Dakota (Former Board Member), Sioux Empire United Way (Former Board Member & Campaign Chair)

• Former CFO and Principal of Insight Energy, VP and Treasurer of NRG Energy, and held financial positions with the following companies: Land O' Lakes, Northwest Airlines, Minnesota Viking Ventures, and Deluxe Corporation

• Earned MBA in Finance from the University of Minnesota and double major undergraduate degree in Accounting and Finance from the University of Wisconsin - Eau Claire. Holds a Certified Public Accounting certificate

2

Experienced and Engaged Board of Directors

Linda Sullivan

Board Chair

Independent Joined April 2017

Brian Bird

Director, President & Chief

Executive Officer

Non-Independent Joined January 2023

Sherina Maye Edwards

Director

Governance, Compensation

Independent

Joined April 2023

Dave Goodin

Director

Audit,

Operations

Independent Joined December 2024

Jan Horsfall

Director

Operations (Chair), Audit

Independent

Joined April 2015

Britt Ide

Director

Governance (Chair), Compensation

Independent Joined April 2017

3

Kent Larson

Director

Audit, Operations Independent

Joined July 2022

Mahvash Yazdi

Director

Compensation (Chair), Operations

Independent Joined December 2019

Jeffrey Yingling

Director

Audit (Chair), Governance

Independent Joined October 2019

Strong Executive Team

Brian Bird

President &

Chief Executive Officer

Current position

since 2023 (formerly President

& Chief Operating

Officer '21-'22 and Chief Financial Officer '03-'21)

Crystal Lail VP & Chief Financial

Officer

Joined company in

2003, current

position since 2021 (formerly VP and Chief

Accounting Officer '20-'21)

Shannon Heim

General Counsel & VP - Federal

Government Affairs

Joined company in 2020, current position

since 2023

Bleau LaFave

VP - Asset

Management &

Business

Development

Joined company in 1994, current position

since 2023 (formerly Director of Long-Term Resources '12-'23)

Jason Merkel

VP - Distribution

Bobbi Schroeppel

VP - Customer Care, Communications,

& Human Resources

Jeanne Vold

VP - Technology

Joined company in 1993, current position

since 2022

Joined company in 1998, current position

since 2002

Joined company in 1999, current position since

2021 (formerly Business

Technology Officer '12-'21)

4

Thank you and Farewell to John Hines and Mike Cashell

"We would like to thank John Hines and Mike Cashell for their combined 60+ years of dedicated service to NorthWestern. John's leadership over two decades, most recently as Vice President of Supply and Montana Government Affairs, played a critical role in rebuilding our generation portfolio in Montana and shaping our energy future. Mike's remarkable 40-year career, most recently serving as Vice President of Transmission, greatly strengthened our operational foundation and reinforced a culture rooted in safety, reliability, and trust. Their insight, leadership, and commitment have contributed significantly to the success of this company and to the benefit of our shareholders, customers, and employees. We are deeply grateful for their service and wish them both the very best in retirement.

- Brian Bird, CEO

5

NWE's Auditors - Deloitte & Touche LLP

• Independent registered public accounting firm

• Deloitte provides the following services for more than 20 industries:

  • Risk & Financial Advisory

  • Audit & Assurance

  • Consulting

  • Tax

  • Merger & Acquisition

  • Artificial Intelligence and Analytics

  • Cloud

• Deloitte and its subsidiaries have over 470,000 professionals

6

NWE's Board Chair

Linda Sullivan

• Director since April 27, 2017

• Retired Executive Vice President and Chief Financial Officer (CFO) of American Water Works Company, Inc., the largest publicly traded U.S. water and wastewater utility (2014-19)

• 22 years of experience with Edison International Companies, last serving as Senior Vice President and CFO at Southern California Edison (2009-14)

• 35-plus years of utility, finance, and regulatory experience

• Certified Public Accountant (inactive) and Certified Management Accountant

• Serves on the board of directors for PPL Corporation, a regulated energy

  company (NYSE: PPL)

  Meeting Agenda

  • Call to Order

  • Secretary's Report

  • Declaration of Quorum

  • Statement of Business

  • Voting

    7

  • Company Presentation

  • Report of Preliminary Voting Results

  • Adjournment

    Corporate Secretary's Report

    Report

    • Affidavit of distribution for the proxy materials

    • Registered holders of common stock of the Company

    • Establishment of a quorum

    8

    Items of Business to be Considered

    
    
    

    Proposal No. 1

    Election of Directors

    Proposal No. 2

    
    
    

    • Our Board is nominating nine people to serve as directors for one year, until the next annual meeting of shareholders (or until a successor is able to serve) or, if earlier, the consummation of the NWE-BKH Merger.

      Ratification of Deloitte & Touche LLP, as Independent Registered Public Accounting Firm for 2026

      Proposal No. 3

      
      
      

    • Our Audit Committee oversees the integrity of our accounting, financial reporting, and auditing processes. To assist with those responsibilities, the committee has appointed Deloitte & Touche LLP as our independent registered public accounting firm to audit our financial statements for 2026.

      Advisory Vote to Approve Named Executive Officer Compensation

    • Our Board will consider the guidance received by the say-on-pay vote when determining executive pay for the remainder of 2026 and beyond.

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Electronic Voting

• If you have not voted: Please use the virtual meeting voting platform to cast your vote now.

• If you previously voted but want to change your vote: Please use

the virtual meeting voting platform to cast your new vote now.

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Forward-Looking Statements

Information in this communication, other than statements of historical facts, may constitute forward-looking statements, within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. These statements include, but are not limited to, statements about the benefits of the proposed transaction between NorthWestern and Black Hills, including future financial and operating results (including the anticipated impact of the transaction on NorthWestern's and Black Hills' respective earnings), statements related to the expected timing of the completion of the transaction, the plans, objectives, expectations and intentions of either company or of the combined company following the merger, anticipated future results of either company or of the combined company following the merger, the anticipated benefits and strategic and financial rationale of the merger, including estimated rate bases, investment opportunities, cash flows and capital expenditure rates and other statements that are not historical facts. Forward-looking statements may be identified by terminology such as "may," "will," "should," "targets," "scheduled," "plans," "intends," "goal," "anticipates," "expects," "believes," "forecasts," "outlook," "estimates," "potential," or "continue" or negatives of such terms or other comparable terminology. The forward-looking statements are based on NorthWestern and Black Hills' current expectations, plans and estimates. NorthWestern and Black Hills believe these assumptions to be reasonable, but there is no assurance that they will prove to be accurate.

All forward-looking statements are subject to risks, uncertainties and other factors that may cause the actual results, performance or achievements of NorthWestern or Black Hills to differ materially from any results expressed or implied by such forward-looking statements. Such factors include, among others, (1) the risk of delays in consummating the potential transaction, including as a result of required regulatory and shareholder approvals, which may not be obtained on the expected timeline, or at all, (2) the risk of any event, change or other circumstance that could give rise to the termination of the merger agreement, (3) the risk that required regulatory approvals are subject to conditions not anticipated by NorthWestern and Black Hills, (4) the possibility that any of the anticipated benefits and projected synergies of the potential transaction will not be realized or will not be realized within the expected time period, (5) disruption to the parties' businesses as a result of the announcement and pendency of the transaction, including potential distraction of management from current plans and operations of NorthWestern or Black Hills and the ability of NorthWestern or Black Hills to retain and hire key personnel, (6) reputational risk and the reaction of each company's customers, suppliers, employees or other business partners to the transaction, (7) the possibility that the transaction may be more expensive to complete than anticipated, including as a result of unexpected factors or events, (8) the outcome of any legal or regulatory proceedings that may be instituted against NorthWestern or Black Hills related to the merger agreement or the transaction, (9) the risks associated with third party contracts containing consent and/or other provisions that may be triggered by the proposed transaction, (10) legislative, regulatory, political, market, economic and other conditions, developments and uncertainties affecting NorthWestern's and Black Hills' businesses; (11) the evolving legal, regulatory and tax regimes under which NorthWestern and Black Hills operate; (12) restrictions during the pendency of the proposed transaction that may impact NorthWestern's or Black Hills' ability to pursue certain business opportunities or strategic transactions; and (13) unpredictability and severity of catastrophic events, including, but not limited to, extreme weather, natural disasters, acts of terrorism or outbreak of war or hostilities, as well as NorthWestern's and Black Hills' response to any of the aforementioned factors.

Additional factors which could affect future results of NorthWestern and Black Hills can be found in NorthWestern Energy's Annual Report on Form 10-K, Quarterly Reports on Form 10-Q, and Current Reports on Form 8-K, and Black Hills' Annual Report on Form 10-K, Quarterly Reports on Form 10-Q, and Current Reports on Form 8-K, in each case filed with the SEC and available on the SEC's website at http://www.sec.gov.

NorthWestern and Black Hills disclaim any obligation and do not intend to update or revise any forward-looking statements contained in this

11 communication, which speak only as of the date hereof, whether as a result of new information, future events or otherwise, except as required by federal securities laws.

Brian Bird

President & CEO

Guiding Principles

NorthWestern Energy Group, Inc.

dba: NorthWestern Energy Ticker: NWE (Nasdaq)

12 https://www.northwesternenergy.com

Corporate Support Office 3010 West 69th Street Sioux Falls, SD 57108 (605) 978-2900

Director - Corporate Development & Investor Relations Officer

Travis Meyer 605-978-2967

travis.meyer@northwestern.com

NWE - An Investment for the Long Term

Pure Electric &

Gas Utility

Solid Utility

Foundation

Earnings &

Cash Flow

Attractive

Future Growth Prospects

Financial Goals

& Metrics

Best Practices

Corporate Governance

• 100% pure electric and natural gas utility with over 100 years of operating history

• Solid economic indicators in service territory

• Diverse electric supply portfolio ~52% hydro, wind, & solar

• Residential electric and gas rates below national average

• Solid system reliability

• Solid JD Power Overall Customer Satisfaction scores

• Disciplined maintenance capital investment program

• Recent rate reviews aid earnings, cash flow, and balance sheet strength

• NOLs and tax credits expected to mitigate future cash tax obligations into 2029

• History of consistent annual dividend growth

• Data centers and other new large-load opportunities

• FERC regional transmission

• Incremental generating capacity (subject to successful resource procurement bids)

• Target 4%-6% EPS growth plus dividend yield to provide competitive total return

• Target dividend long-term payout ratio of 60%-70%

• Target debt to capitalization ratio of 50%-55% with liquidity of $100 million or greater

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5th Best Governance Score

About NorthWestern

South Dakota Operations

Electric

65,600 customers

3,730 miles - transmission & distribution lines 420 MW nameplate owned power generation

Natural Gas

51,200 customers

1,908 miles of transmission and distribution pipeline

Montana Operations

Electric

440,700 customers

25,542 miles - transmission & distribution lines

1,660 MW maximum capacity owned power generation

Natural Gas

249,400 customers

8,072 miles of transmission and distribution pipeline

17.85 Bcf of gas storage capacity

Own 25.3 Bcf of proven natural gas reserves

Nebraska Operations

Natural Gas

43,400 customers

836 miles of distribution pipeline

14 Data as of 12/31/2025

About Our Company

850,300

Customers

MT - 690,100

SD/NE - 160,200

1,667

Employees

MT - 1,353

SD/NE - 314

339

Communities in Montana and South Dakota with electric service MT - 223 (99 electric only / 124 combo)

SD - 116 (74 electric only / 42 combo)

234

Communities in Montana, South Dakota, and Nebraska with natural gas service

MT - 148 (24 gas only / 124 combo)

SD - 82 (40 gas only / 42 combo) NE - 4 gas communities

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Data as of December 31, 2025

$5.6 Billion

Rate Base

MT - $4.6 billion

SD/NE - $1.0 billion

$548.6 Million

Capital Expenditures in 2025

MT - $448.6 million SD/NE - $100.0 million

$8.5 Billion

Total Assets

MT - $7.0 billion SD/NE - $1.5 billion

$174.2 million

Property Taxes MT - $167.4 million SD/NE - $6.8 million

Lone Peak, Big Sky, MT

A Diversified Electric and Gas Utility

16

Data as reported in our 2025 10-K

2025 - Year In Review

Executing on Strategic Initiatives

• Announced agreement with Black Hills Corporation for an all-stock Merger of Equals

  • To create a premier regional regulated electric and natural gas utility company

• Closed acquisition of Avista and Puget Colstrip interests

  • Providing resource adequacy in Montana, increasing plant ownership from 15% to 55%, and supporting potential large-load integration

• Submitted $300M (131MW) South Dakota natural gas project to SPP's expedited resource adequacy study

  Lake McDonald, Montana

  
  
  

• Acquired Energy West and Cut Bank Gas natural gas distribution assets

  Legislative & Regulatory Outcomes

• Montana SB301 signed into law, providing greater confidence for transmission investment in Montana

• Montana HB490 signed into law which clarifies and limits wildfire-related

  risks, protecting our customers, communities, and investors

• Approval of Wildfire Mitigation Plan in Montana

• Completed Montana Electric & Natural Gas general rate reviews

  • Providing recovery of our significant investment to reliably serve our customers

    Advancing Data Center Growth Opportunities

• Signed third letter of intent with Quantica for a 500+ megawatt data center

• Progressed Sabey letter of intent to a development agreement

17

Merger with Black Hills Benefits Stakeholders

Increases Scale

Position and Growth

Increases the combined company target EPS growth rate to 5-7%, supported by the doubling of each company's rate base to total of ~$11 bn with significant growth opportunities

Expands

Investment Opportunity

Leverages enhanced resources to make strategic investments that foster economic development, including addressing the growing demand for energy, including from data centers

Substantial Long-Term Value for Customers

Bringing together two complementary teams focused on reliability and exceptional customer service to deliver even greater value.

Strengthens

Balance Sheet

Strong and predictable cash flows support a customer-focused capital investment program while producing high-quality, investment-

grade credit metrics

Enhances Business Diversity

Delivering energy to more than 2.1 mm customers across multiple contiguous jurisdictions, served by a highly skilled workforce focused on safety and reliability

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For more information, see https://www.blackhillsnorthwesternbettertogether.com

The NorthWestern Value Proposition

+

Base Capital Plan:

Approximately 4% Dividend Yield

+

4% to 6% EPS Growth

Incremental Opportunities:

> 6% EPS Growth

=

8% to 10% Total Return

19

2026-2030 Capital Investment

($ Millions)

• Data centers & new large-load opportunities

• FERC Regional Transmission

• Incremental generating

capacity

(subject to successful resource procurement bids)

=

>10% Total Return

Reliability

CC.C7C% Uninterrupted Reliability

* System Average Interruption Duration Index (SAIDI) is the total number of minutes interruption the average customer experiences. The numbers shown here reflect data reported to IEEE, including

20 planned outages but excluding Major Event Days and Catastrophic Events per IEEE methodology.

Exceeding industry reliability standards… a remarkable achievement given our rural, rugged, and dispersed service territory.