The Belgian international enjoyed a hugely successful loan spell with the Saints after joining from Atletico Madrid on deadline day at the beginning of the season.
Southampton have an option to buy for around £6.8million but it understood Atletico could revoke that by making a payment.
If that occurred the Spanish club could either keep him or sell elsewhere, and both Manchester City and Tottenham have been linked with the 26-year-old.
Alderweireld admits he does not know what lies ahead but, after moving from Ajax to Atletico in 2013 and then to Saints last year, he is hoping his future is resolved as soon as possible.
He said: “I hope to know where my future is before pre-season starts because it’s two years in a row that I have done a pre-season with a club and then on August 31 I have left.
“So I hope this time I can do a pre-season with the club that I will be playing with and have a good year.
“The situation is frustrating and I don’t know what will happen. I would like to make a decision but the club has to decide first.
“There are three options – stay with Atletico, stay with Southampton or go to another club. So we will see what happens.
“It’s not up to me so I can’t say a lot about it but I hope the decision is quickly made.”
Alderweireld feels he settled in well at Southampton and enjoyed playing in Ronald Koeman’s impressive team.
Saints, despite being written off at the start of the campaign after losing several star names, finished seventh and could yet qualify for the Europa League.
Alderweireld said: “I really enjoyed the Premier League. I’ve had a fantastic year at Southampton and I want to thank the fans and the club for giving me the opportunity.
“The diversity is nice, the tempo, the atmosphere at games and the language is better for me than in Spain.
“I’ve had a fantastic year, I can’t lie about that, so yes I’d like to stay in the Premier League.
“I really want to go to a club that really wants me. Southampton gave me that opportunity and it paid off, I think.”