Good question...actually here in the tropical climate, there really isn't an "off" season per se. There are only seasons for specific foods. There are fresh local foods all year around.
Right now, the avocados are getting too expensive to buy again, because they are almost totally out of season. But the lovely mango fruit are starting to get very large and cheaper because they are in season. Oh, so yummy too!
The idea of refrigeration, freezing or canning produce doesn't really happen here for the majority of people. Because many do not have electric or even the space to store home canned goods plays into this. There are some stores in Accra (capitol) where supplies can be procured to do things like freezing or canning, so it's not impossible. But really, those supplies are there generally because of the expats (foreigners living in Ghana) that would buy them to do such things.
What you might find however is preservation by ground storage, drying, smoking, salting or other similar method that does not involve electricity. That's how many of our own ancestors preserved food before such modern conveniences.
The seasonal question is still valid here however, because of the planting and harvesting of certain foods at different times of the year. That mostly applies to fruits and vegetables, but for beans and grains, those can be bought at the markets anytime of the year.
A couple of weeks back, I bought a fresh white yam. It was not from storage, but rather had just been harvested. I thought I'd like to try a fresh yam to see the difference, thinking that it would taste much better and richer, etc. than the stored ones I had been buying. Believe it or not, we did not prefer it. It didn't taste as good as the stored ones. I don't really know why, but maybe that "aged" flavor is just better.
Each seems to have its own season: cassava, plantain, white yam, corn (maize). When it's corn season, you'll notice people selling it grilled or boiled. Then another time, it will be the plantains that are cheap. It's like this all year around. The food places on the street will change what they sell based on the in season foods. Rice can be found all year around, but lately prices have been going up here, just like in other parts of the world.
If there are places to buy stews, the main vegetable will vary depending on the produce available. Even sit down restaurants may not have half their menu available because it all depends on the season.
They really do eat locally and in season here. It's cheaper and some people grow much of their own food, if they have any land to speak of. No yards here, but maybe corn or cassava growing.I think that that is where its at for everyone concerned with food availability and prices. Grow your own. If that's not possible, then eat locally and in season.
Know your food and grow some too. Gardens are good for the whole family! I can't wait to start one myself next year after we settle back in the states again. Until then, I'll try to find some good farmer's markets to go to.