With temperatures soaring higher than average this year, retailers are hoping to boost sales of apparel by capitalizing on the government's annual Cool Biz campaign, which started Tuesday.

To reduce energy costs, the Cool Biz campaign calls for workplaces to set their air conditioners to 28 degrees, and urges office workers to ditch the usual ties, jackets and office wear in favor of casual clothes more suitable for Japan's hot summers.

For the month of April, Tokyo's daily highs exceeded 25 degrees on nine occasions, an all-time record. This prompted department store operator Takashimaya Co. to start its own Cool Biz summer clothes campaign on April 11, one week earlier than usual.