Investor Presentaiton

26 26 r 2020 Electric Generation Portfolio - Total NWE Wind Contracted 23.0% Wind Owned 6.6% ESG - Environmental 2020 Carbon-Free Owned & Long Term Contracted Nameplate Generation Resources (As a Percentage of Total Nameplate MW Capacity) 65% Carbon-Free 70% Geothermal/Other Pumped Storage GOOOO Contracted CELP & YELP 9.7% Natural Gas Contracted 0.8% Natural Gas/- Other Owned 2.7% Coal Owned 21.9% DOODD NWE 60% Hydro Montana & Owned Solar South Dakota combined 33.5% 50% Hydroelectric Wind 40% Nuclear Hydro Contracted 1.5% 30% Solar Contracted <1% Based upon 2020 MWH's of owned and long-term contracted resources. 65% of NorthWestern Energy's 2020 Electric Generation Portfolio Delivered was Carbon-Free Mystic Dam 20% 10% 29% 34% 65% 57% (based on megawatt hours) 0% Beethoven Wind Farm United States (2019) NorthWestern (South Dakota) NorthWestern (Montana) NorthWestern (Total Company) 57% Carbon Free Nameplate Portfolio VS 29% National Average in 2019 (based nameplate megawatts)

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