The campaign, which breaks on 1 September, invites potential holiday makers to "experience the new season's colours from Wales". It is designed to make consumers aware of all Wales has to offer at this time of year.
"It is vital that we give people concrete reasons for coming to Wales during autumn and show them that holidays don't need to come to an end after the August Bank Holiday. There is plenty to do in Wales whatever the season," Roger Pride, the marketing director at the Wales Tourist Board, said.
HHCL has designed a roll-fold leaflet that presents Wales against the backdrop of a classic paint colour chart.
The leaflet uses tones and hues - named "September moods", "October accents" and "shades of November" - together with suggested activities and locations to provoke readers into imagining what they are missing in Wales.
"We wanted to appeal to the reader's imagination, evoking a distinct feeling of what inevitably is a unique experience in Wales, especially in autumn," Jonathan Adler, the account director at HHCL/Red Cell, said. "And we wanted to use something people were familiar with."
The campaign was written by Andrew Lloyd-Jones and art directed by Mark Dickens. Media planning and buying is through Media Insight.
The work is a continuation of the £10 million "Wales the big country" campaign now in its second year.