McAuley has not played for new club Rangers, while Washington asked to miss the games for personal reasons.
"I spoke to Rangers and we decided it was in Gareth's best interests not to be with us for this trip. He's still not fully fit and hasn't played a game since Costa Rica at the start of June," Michael O'Neill told reporters.
NI face Austria in Vienna on 12 October and Bosnia in Sarajevo on 15 October.
Here is the squad in full:
October 3, 2018
Northern Ireland squad
Goalkeepers: Michael McGovern (Norwich), Trevor Carson (Motherwell), Bailey Peacock-Farrell (Leeds).
Defenders: Craig Cathcart (Watford), Jonny Evans (Leicester), Aaron Hughes (Hearts), Tom Flanagan (Sunderland), Conor McLaughlin (Millwall), Paddy McNair (Middlesbrough), Michael Smith (Hearts), Jamal Lewis (Norwich).
Midfielders: Steven Davis (Southampton), Niall McGinn (Aberdeen), Stuart Dallas (Leeds), Corry Evans (Blackburn), Shane Ferguson (Millwall), George Saville (Middlesbrough), Jordan Jones (Kilmarnock), Oliver Norwood (Brighton, on loan at Sheffield United), Gavin Whyte (Oxford United).
Forwards: Kyle Lafferty (Rangers), Liam Boyce (Burton), Josh Magennis (Bolton), Will Grigg (Wigan), Jamie Ward (Nottingham Forest, on loan at Charlton).