>>49297
>Fly agaric needs some temperature to grow, not hot, but "Arctic" communities, nah, perhaps on taiga.
I looked into where Amanita muscaria grows, and it's fairly diverse. There's speculation of it originating in colder areas, such as the Siberian and Beringian area, which is where the indigenous people doing the mushroom-reindeer ritual resided.

https://www.gbif.org/species/113534033
"A recent molecular study proposes that it had an ancestral origin in the Siberian–Beringian region in the Tertiary period, before radiating outwards across Asia, Europe and North America."

https://web.archive.org/web/20110716142858/http://www.lter.uaf.edu/pdf/1190_Geml_Laursen_2006.pdf
"The ancestral population of A. muscaria likely evolved in the Siberian–Beringian region and underwent fragmentation as inferred from NCA and the coalescent analyses. The data suggest that these populations later evolved into species, expanded their range in North America and Eurasia. In addition to range expansions, populations of all three species remained in Beringia and adapted to the cooling climate.

I'm unsure when they grow in these specific areas, perhaps they are able to adapt to grow during colder months (such as December), but I did not find much to support this, maybe it's something I will look into more later. All I found were mentions of the mushrooms being piled under snow, in which reindeer would find and eat. However, there's likely more solid evidence either in favor (or not) of this.

https://www.reed.edu/biology/courses/BIO342/2014_syllabus_old/2014_WEBSITES/james_fisher-smith_jesse_duham_drugs&behavior/ReindeerFlyAgaric.html
"(Amanita muscaria) has a religious significance in Siberian culture, specifically the Tungusic, a reindeer herding indigenous people. It is assumed that herders observed their reindeer’s habit of seeking out these hallucinogenic mushroom and decided to try it out themselves. According to Samorini, though these reindeer typically march in a straight line, they will break form to chase after and dig up (even under snow cover) these mushrooms. it is unclear if the reindeer have come to recognize these mushrooms as sources of nutrition, or they seek the psychedelic effects that accompany them. To this day the Tungusic consume the Amanita muscaria mushroom entheogenically, either raw or distilled in the urine of their reindeer."

I found more information about the indigenous people in these cold climates using Amanita muscaria for both spiritual and intoxicating purposes, so while they may have drank reindeer urine to get the effects of the mushroom, it's possible it was not during the winter solstice depending on if the mushrooms grow during that time. I saw that these mushrooms grow in summer-autumn in the North America and autumn-winter in the pacific coast, but not sure specifically to the Siberian area. There must be evidence one way or another to clarify when these mushrooms grow in this specific area.
"A local variety of the mushroom was used as an intoxicant and entheogen by the indigenous peoples of Siberia and by the Sámi, and has a religious significance in these cultures."