EXHIBIT 99(b) CERTIFICATION OF PERIODIC REPORT I, James K. Vizanko, Vice President, Chief Financial Officer and Treasurer of ALLETE, Inc. (Company), certify pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, 18 U.S.C. Section 1350, that: 1. The Quarterly Report on Form 10-Q of the Company for the quarterly period ended September 30, 2002 (Report) fully complies with the requirements of Section 13(a) of the Securities Exchange Act of 1934 [15 U.S.C. 78m or 78o(d)]; and 2. The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company. Dated: November 1, 2002 James Vizanko -------------------------------- James K. Vizanko Vice President, Chief Financial Officer and Treasurer