Vaisala Corporation ANNOUNCEMENT 25.5.2012 SHARE REPURCHASE 25.5.2012 In the Helsinki Stock Exchange Trade date 25.5.2012 Bourse trade Buy Share VAIAS Amount 130.000 Shares Total cost 1.969.500,00 EUR Average price/ share 15,1500 EUR Highest price/ share 15,15 EUR Lowest price/ share 15,15 EUR Vaisala Corporation now holds a total of 147.299 shares including the shares repurchased on 25.5.2012. On behalf of Vaisala Corporation Nordea Bank Finland Plc Petri Simberg Julius Summanen