How far north into zone 9 are you? If you are in zone 9b then you probably would be fine planting it. Satsumas are more cold hardy than most oranges that's why they are more popular in the more northern parts of zone 9. If you don't want to take any chances then pot it up to a larger pot and keep it in a warm place, such as a garage, during freezing nights. Then plant it during the end of Feb. or early March next spring. If you plant it now then be sure to protect it when the temps. dip below freezing. The tree will become more cold hardy as it grows larger.

Christine

Thanks for the info Christine - I'm in zone 9 near Tampa. I'll probably plant it and just protect it and hope for the best.

Yeah, I would plant it now in the Tampa area.

The nice thing about citrus planted in ground in Florida , is that it is OK to plant them at almost any time of the year . Fall is a wonderful time to plant trees of any kind .
Do not fertilize any citrus until the Spring .
Do not add anything to the soil . Dig a hole and use the same soil to fill the hole .
Plant higher as opposed to lower .
Water , water , water . Water frequently for one entire year .
Do not prune any tree after planting .
I have older Satsuma trees . They are the first to bear fruit and everyone's favorite . They used to be called zipper tangerines . The trees are somewhat smaller than other citrus and have alternate bearing years . Last year they produced a large crop - this year minor . Enjoy your new tree !
Here is one of many helpful links on citrus :

Here is a link that might be useful: Citrus Guide - Young Tree Care