How about a Black-eyed Susan vine?

Here is a link that might be useful: Black-eyed Susan vine

The Allamanda or yellow Black Eyed Susan/Thunbergia will probably be the longest blooming. Thunbergia has many more flowers over the season, and will continue to bloom here in California as long as it is warm enough. The Allamanda certainly has larger, more dramatic individual flowers. Not sure if it is commonly planted in your region, but the Australian vine, Hibbertia suaveolens is another very long season bloomer with both nice waxy foliage and large yellow blooms. I also like the South African Senecio tamoides vine, but this one blooms in late fall into winter, but is simply covered with flowers when in bloom.

A Canary Creeper Vine (Tropaeolum peregrinum) is an annual here in zone 7 that has pretty yellow blooms. It doesn't start flowering until mid summer but continues until the frost. It might be a perennial in your zone.
Karyn

Blacked eyed susies grow easy from seed too.

Thanks for all the good suggestions. I had to look up the Hibbertia suaveolens- I never heard of that one lol. It is pretty. I do have a yellow mandevilla (it started blooming in summer last year and went through about November here)that I could put on one side of the trellis with one of other vines mentioned. I have seeds of canary creeper and black eyed susan- I could put both on the other side, that should give enough yellow color. The blue vine I have is blue skyflower, and I have white mandevillea and some madagascar jasmine to make up my blue and white colors. I will post a picture later this year if it comes out well. Thanks for all your help.
~SJN

oops that should of said, "I have a yellow allamanda" lol.
Angie forgot to thank you for posting that pretty cheerful photo. Nice and bright to see for this time of year :)
~SJN

Black-eyed Susan vine is my favorit vine!

Here is a link that might be useful: Cat Names