Vaisala Corporation ANNOUNCEMENT 28.5.2012 SHARE REPURCHASE 28.5.2012 In the Helsinki Stock Exchange Trade date 28.5.2012 Bourse trade Buy Share VAIAS Amount 730 Shares Total cost 11.048,30 EUR Average price/ share 15,1347 EUR Highest price/ share 15,16 EUR Lowest price/ share 15,11 EUR Vaisala Corporation now holds a total of 148.529 shares including the shares repurchased on 28.5.2012. On behalf of Vaisala Corporation Nordea Bank Finland Plc Petri Simberg Julius Summanen