I know 'spices' is a uselessly broad category, but is there a reason that cinnamon, nutmeg, cloves, etc. are so closely associated with the Christmas season (at least in the West)?
This is NOT an answer to your question, but I'l point out that fresh produce was not available in the winter.
I can answer half of the question with an academic source, and narrow the window on the other half of the question with non-academic sources.
/u/sinisterstarr was on the right track. Many spices including cloves and cinnamon are natural preservatives. By the time the holidays rolled around, people would have been eating preserved produce.
Nutmeg originally comes from Indonesia.
Cloves come from Indonesia too
Cinnamon (actually a number of different plants pass as "cinnamon") comes from Ethopia, India, Sri Lanka, and other eastern countries.
So, we can narrow the window down to after the time at which Europeans had reliable trade routes with Indonesia and the other countries listed above.
I wonder if the answer to your question might be found by asking it in reverse: when did those spices fall out of favor in the warmer months? They were used in sweety and savory (upper class) dishes right through the 17th century at least. I'm just going to leave this link, individual recipes have source material: http://www.godecookery.com/ ...By the late 18th century, the recipes I've seen use spices much less often in savory foods, with the exception of things like making beef to taste like venison. Granted, most of my texts from this period are Colonial American, so I'm not sure if this was the same in England.
Going out on a limb with a theory and I tried to find dates or supporting evidence with this part (and failed)... maybe someone can find better evidence. I think due to the fact that spices had mostly been limited to nobility (due to sumptuary laws), when these laws were loosened (or more easily circumvented) the middling class could offer them as conspicuous consumption to guests, or at celebrations. Traditionally, winter holidays, like Christmas, are the most lavish in Christian/western countries. This may be why we continue to use these spices during winter but only in sweet (celebratory) foods like cake the rest of the year.
Could you specify where this association is made? I live in Western Europe and have never heard a link or association between said spices and the winter holidays.