It´s only in German, but it has a contact email : wienerland@.... In the PROGRAMM section I have found some walks for October, that might interest you :

Sa, 12.10. % VW Wien 16, 24. Millenniums-Wandern, 10 km, T 15.00, Linie 45, Endstelle, An der Scheibenwiese Su, 13.10., Busfahrt zum Litschauer Marathon Mo, 14.10. % VW Wien 9, U-Bahn-Wandern, 10 km, T 17.00, U 2 Schottentor Tue, 15.10. % VW Wien 20, S-B.-W., 10 km, T 17.00, S-Bahn-Hst. Handelskai Fr, 18.10. % VW Wien 21, WWW, 10 km, T 18.00, S-Bahn-Hst. Strebersdorf Fr, 18.10. % SW Weinviertelmarsch, Wien - Stockerau - Langenzersdorf, 60/100 km, T 18.00, S-Bahn-Hst. Strebersdorf Sa, 19.10. % SW Weinviertelmarsch, Stockerau - Langenzersdorf, 40 km, T 5.45, Stockerau, Bhf Mo, 21.10. % VW Wien 10, U-Bahn-W., 10 km, T 17.00, U 1 Reumannplatz

Some of them are in Vienna, and on the 18th and 19th of October there is a long walk in the Weinviertel, an interesting region north of Vienna, between Austria and Slovakia : http://www.weinstrasse.co.at/ http://www.weinviertelfestival.at/

And a bit farther from Vienna, the Hohe Tauern National Park could be an option : http://www.hohetauern.at/ or http://makeashorterlink.com/?L12624741

Kind regards, Covadonga Bilbao - Spain