All up, more than 40 bands will play up to three times each at seven venues in Paihia, Russell and Haruru Falls.
The action starts at 6pm tonight and continues until Sunday night.
Bands will perform on the streets around Paihia in the mornings, before the music heads indoors at noon.
Mrs May said reaching 30 years was a major achievement for any event. She has organised the past 22.
Regular favourites include Blue Monkey Racket, Brilleaux and Lex Pistols, a group of swing-playing Auckland lawyers who have performed at every festival to date.
Northland acts taking part include Basin City Big Band, Jireh May and Mike Nettmann, Joe Carbery Trio, Late Night Meat Sandwich, Soulshine, Taylah Barker and Two Kay.
Entry badges cost $50 from the venues; day passes are $30. See www.jazz-blues.co.nz for more information.