EXHIBIT 99(a) CERTIFICATION OF ANNUAL REPORT I, David G. Gartzke, Chairman, President and Chief Executive Officer 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 Annual Report on Form 10-K of the Company for the year ended December 31, 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: February 14, 2003 David G. Gartzke ------------------------ David G. Gartzke Chairman, President and Chief Executive Officer