Ashdown will play for the Cherries' reserve side tomorrow before formally signing tomorrow.
Alan Pardew expects his young keeper to be a first team regular during his short-term spell with the Cherries - displacing the South Coast side's number one Gareth Stewart.
Jamie Ashdown is a very highly-rated young goalkeeper. Jean Tigana was understood to be keen on taking him to Fulham last year, whilst his French conterpart Arsene Wenger had him at Highbury on loan for the final month of last season.
Despite Phil Whitehead and Marcus Hahnemann blocking his path Ashdown's long-term goal of breaking into the Reading first team remains.
Meanwhile, Joe Gamble last night made an appearance for the Republic of Ireland under 21 side against Finland. The Irish won the game 1-0 thanks to a last minute winner.
Gamble featured on the right of midfield although he usually plays in the centre for the Royals.
The former Cork City player will watch the Irish senior side in action tonight before flying home tomorrow.