I don't see ppl pointing this out much but the yearly weather cycle in the world of 3Houses is based more on that of Japan than the typical four seasons in the West. So I will list them out here cuz I love the worldbuilding of 3H :3 This will be based on the narration for each month.
An interesting thing I want to note is that the numbers used to help us identify which Imperial Moon correlates to which Gregorian Month (like Great Tree Moon - 4 -> Apr or Ethereal Moon - 12 -> Dec) were, in-universe, actually from an old Fódlani calendar that predates the Imperial calendar :> You can think of it like how many countries still use both the Gregorian calendar and a lunar calendar.
The way the Imperial calendar was imposed in Fódlan is pretty much a direct reference to our modern calendar.
But I digress... This is supposed to be about the Seasons of Fódlan🍃🌹🌨️🌕
🌱 Spring starts in Great Tree Moon (Apr). It is also the start of a new Imperial year, with the Adrestian Empire Founding Day being on the 1st.
"The icy winds of the Oghma Mountains have begun to scatter, and the verdant fields once again spring to life across Fódlan, heralding the start of a new year. As they celebrate the dawning year, the people pray that they may realize their full potential, just as a tiny sprout hopes to one day grow into a great tree."
🌧️ Summer, aka the rainy season, starts in Garland Moon (Jun).
"When the warm winds blow from the from the sea to the south of Adrestia, residents of Fódlan know that the rainy season is upon them. Before the heavy rains take their toll, the young women hurry to pick the last of the white roses. The ivory buds are woven into garlands and given as gifts to close friends or potential lovers."
🌾 Fall starts in Horsebow Moon (Sep).
"As cold air begins to creep in from the north of Faerghus, Fódlan welcomes the riches of fall. The women spend their days reaping the golden fields, gratefully embracing the bounty the goddess has once again provided. The men venture into the wild with horsebows and empty sacks ready to be filled with game."
❄️ Winter starts in Red Wolf Moon (Nov).
"Hoarfrost now graces treetops and open fields alike, and an icy chill blown in from the north of Faerghus blankets the land. All of Fódlan's creatures begin to settle in for a long winter. The setting sun bathes the full winter coat of every wolf in a foreboding scarlet glow. Hunters can now spread the word that the red wolves are back on the prowl."
🌱 lasts 2 months: Great Tree & Harpstring Moon
🌧️ lasts 3 months: Garlands, Blue Sea & Verdant Rain Moon
🌾 lasts 2 months: Horsebow & Wyvern Moon
❄️ lasts 5 months: Red Wolf, Ethereal, Guardian, Pegasus & Lone Moon
Jeralt wasn't kidding when he said winter would be long, huh...
🌟 One particular detail the narrations deemed important to point out is the appearance of the Blue Sea Star, aka the Goddess' Home, aka the star Sirius, which is behind two very important names in this game, "Sothis" and "Seiros".
The Blue Sea Star can be seen in Fódlan's sky from Blue Sea Moon (Jul) till Red Wolf Moon (Nov). This somewhat matches our Sirius being a winter star in the Northern Hemisphere.
Ethereal Moon: "... the Blue Sea Star has gone back into hiding..."
🌬️ Another piece of info given be the narrations is that the weather system in Fódlan is maintained by warm, humid wind from the South in Summer and cold wind from the North in Winter.
Garlands: "When the warm winds blow from the from the sea to the south of Adrestia, residents of Fódlan know that the rainy season is upon them..."
Horsebow: "... cold air begins to creep in from the north of Faerghus..."
Red Wolf: "... an icy chill blown in from the north of Faerghus blankets the land..."
The Winds of Winter (heh) seem to be quite strong over this continent, to the point where even Southern Adrestia & the sea beyond are chilled. Their effect can be felt for 7 months of the year, with 5 months suffering from frosts & active snowfall.
I'd like to hazard a guess that Fódlan suffers from the same phenomenon that happens to Japan. The dry, cold air from Siberia picks up moisture when it crosses the Sea of Japan, dumping a fk ton of snow onto Northern Japan (this country has 3 of the snowiest cities in the world!).
Similarly, the North of Fódlan where the winter winds blow from is also surrounded by a sea.
Winter in Faerghus must be such a struggle... Although the land there is actually blessed with minerals and oils :))) so maybe what they need to turn their fortune around is a few industrial revolutions :)))))))))
But no I need to stop there. I think too hard and now I'm imagining capitalism in my favorite medieval fantasy. Nope nope nope 🙂↔️
🔎🗓️ Edit: some other fun details I neglected to mention
1) Wyvern is a migratory species which flies to the South in, you guessed it, Wyvern Moon (Oct). Did that have any impact on Fódlani taming them? Does Almyran wyverns migrate? Or is the climate there much warmer and they belong to a different species from Fódlani wyverns?
2) The main grain of Fódlan grows in ~4 months. Seeds are sown in Harpstring Moon (May), and the harvest is in Horsebow Moon (Sep). That seems to be the average for spring wheat? And, well, the rest of their year is winter :)))
Seriously, winter in Fódlan is way too long 🫠
Bonus edit cuz I keep finding weather related info
In chapter 5 Verdant Rain Moon (Aug), Annette tells you to prepare a coat bc Faerghus is chilly even at that time of the year (end of Fódlan summer), and it rains a lot. The Tailtean Plains map, which is in Blaiddyd territory, is also raining
Yk, Faerghus being a perpetually cold & humid hellscape is the kinda condition I imagine Northwestern Europe (the UK, the Netherlands, Denmark) suffer from :Đ No wonder the Faerghan are depressed
I hope you have as much fun reading this as I had while reading the texts to compile these info ( ╹▽╹ )