The overall UK ad market is now expected to rise 2.9% year on year in 2010, up from the 1.3% predicted in April.
In April, ZenithOptimedia predicted that outdoor ad spend would see a 3% rise in 2010, when compared with 2009. Last year the outdoor ad market declined by 16.7%.
Jonathan Barnard, head of publications at ZenithOptimedia, said that, last year, outdoor "prepared itself for the upturn" by culling poor quality sites.
He added: "What that’s done is that the remaining sites are better value. Even though spend is not returning to levels of 2008 or even 2007, the year-on-year comparisons are looking very strong."
Outdoor media owners suggest the rise is due to the return of advertising and brand campaigns.
Dave McEvoy, marketing director at JCDecaux, said: "We took more of a hit than other media last year, but this year outdoor is bouncing back.
"We have seen a rebound in car advertising, and the election and the World Cup have helped. There has been a return to brand advertising this year for lots of advertisers and people have come back to outdoor because it is the biggest brand-building medium."
Outdoor is not the only sector to see a rise; the TV ad market is expected to be up 7% year on year, from 6% in April, and spend on internet advertising is expected to be up 4.6% year on year, from 4% in April.
National newspapers are also expected to see a rise in ad spend for the first time in three years, with ZenithOptimedia forecasting a 2.6% lift year on year.