Hello i came to Thailand with 3 Tourist visas i arrived feb 18 so my first visa runs out on April 18. Now i am supposed to be doing a 3 week meditation retreat from the 1 april-21 april. Which means my current visa expires 3 days before the retreat would end. Would it be possible to get and 30 day extention now on my current visa now, even though its still got like a month left on it? I would be doing it at the Chiang mai office.

and do you think a meditation reatreat is an good enough reason for immagration to accpet the extention request?

Just give it a try, your should be OK. For a tourist visa I would normaly advice 1 week or so in advance, but immigration doesn't make a big deal out of it. Especialy if you give them a good reason.

I went 3 weeks before mine was due , no problems or questions filled in the form paid the 1900baht and on my way home in less than 30 minutes .