Investor Presentaiton

Minutes L NWE's Overall Customer Satisfaction Scores via JD Power Electric & Gas Residential Studies JD Power Scores 740 720 700 680 660 640 620 600 Strong Utility Foundation $1.20 $100 "Typical Bill" Residential Rate Comparison National Average ($105.05) National Average ($95.20) SD MT 580 97.72 90.84 560 MT 76.05 NE SD 60.84 63.13 $10 5.20 580 560 T T 2011 2012 2013 2014 2015 Electric 2016 2017 2018 2019 2020 Natural Gas System Average Interruption Duration Index (SAIDI) Includes MED's - NWE versus IEEE Reliability Quartiles S- Electric (750 kwh) NWE rates as of 1/1/2021 Natural Gas (100 therms) Llectric source: Laison Llectric Institute Typical Lis and Average Rates Report, 1/1/20 Natural Gas source: US EIA- Monthly residential supply and delivery rates as of January 2020 Leaks per 100 Miles of Pipe Excluding Excavation Damages - 2019 AGA 1st Quartile - 8.1 AGA 2nd Quartile - 17.2 280 240 200 160 2nd Quartile 120 80 1st Quartile 40 0 2014 2015 2016 2017 2018 2019 2020 NWE - 2019 8.8 ☐ 0 2 4 6 Solid and improving JD Power Overall Customer Satisfaction Scores ■ Residential electric and natural gas rates below national average ☐ Solid electric system reliability ▪ Low gas leaks per mile – just outside 1st quartile 00 8 10 12 14 16 18 20 NorthWestern Energy Delivering a Bright Future 8

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