The server keeps one time and one calendar for the whole world: every player sees the same hour, the same moon and the same season. The season moves the temperature of every place, and the temperature decides what falls from the sky, whether the snow stays, whether the lakes freeze, how fast food spoils and how the crops grow.
The day
- A whole day, sunrise to sunrise, lasts 1200 seconds: 20 real minutes.
- The sun rises at 6:00 and sets at 18:00: day and night are as long as each other. One hour of the world is 50 real seconds.
- A new world starts at 8:00 on the first day of spring.
- Durations in the game (stations, brewing, spoilage) are counted in this world time.
The calendar
The year is built on the moon:
- The moon goes from new moon to new moon in 8 days. Each of its 8 phases lasts one day: new moon on the first day, full moon on the fifth.
- Eight days make a huitaine, and every huitaine opens on a new moon.
- Three huitaines make a season of 24 days: spring, summer, autumn and winter, in that order.
- Four seasons make the year: 12 huitaines, 96 days, about 32 hours of real time.
The calendar of the HUD shows two lines: the day of the huitaine with the huitaine’s name, then the season and the moon’s phase. The twelve huitaines have names of their own:
| Season | 1st huitaine | 2nd huitaine | 3rd huitaine |
|---|---|---|---|
| Spring | Thaw Moon | Sowing Moon | Blossom Moon |
| Summer | Long Days Moon | Haymaking Moon | Fair Moon |
| Autumn | Harvest Moon | Vintage Moon | Falling Leaves Moon |
| Winter | Frost Moon | Long Night Moon | Returning Light Moon |
Temperature
The climate of a place
Every column of the world has an air temperature, fixed when the world is made:
- Latitude first: from -12 °C at the northern edge of the map to 28 °C at the southern edge, in a straight line.
- Altitude: the ground loses 6.5 °C per 1000 metres above the sea.
- A slow noise of up to about 6 °C either way, so neighbouring valleys differ.
- A small bias per island: Vepre is 1 °C cooler, Givre 1.5 °C cooler (about -5 °C at its heart), and part of Cendree 3 °C warmer.
The biomes are chosen from this temperature and the humidity, so cold places have their own biomes; see Islands and biomes.
The season
The season adds the same offset everywhere, following a smooth curve through four points of the year (it never overshoots them):
| Middle of | Spring | Summer | Autumn | Winter |
|---|---|---|---|---|
| Offset | 0 °C | +6 °C | 0 °C | -8 °C |
This seasonal air is what the crops, the snow, the ice, the weather and the stored food feel. Deep winter brings the snow far south; high summer warms even the north.
What your body feels
Your character feels more than the air of the column:
- Day and night: the air swings by up to 5 °C, warmest at 14:00 and coldest at 2:00.
- Height above the ground: a climb or a flight cools the air by 0.0065 °C a metre.
- Wind: above 600 metres of altitude, the wind chills by 0.02 °C a metre, 12 °C at most.
- Water: swimming (two fifths of the body under or more) you feel the air minus 4 °C, never below 1 °C, and you come out Wet.
- Fire: within 4 blocks of a torch you feel 12 °C warmer.
- Effects: Wet takes 6 °C off and halves the warmth of your clothes; meals such as the black stew (Warmed, +8 °C) or the flatbread (Hardy, +3 °C) warm you; see Food and preservation.
Between 8 °C and 28 °C felt, your body stays at 37 °C; worn warmth lowers the 8 °C. Outside it, your body temperature slowly drifts, and once it strays from 37 °C the HUD shows it beside the bars. Too cold or too hot, you first lose breath, then health; see Creatures and combat.
Weather
Each region of the world (each island, the Dents, the open sea) has its own weather, the same for everyone in it; the Dents and the sea share the same odds. Every world hour (50 real seconds) the region either keeps its weather or draws a new one by the odds of its season.
| Weather | What falls | Average length |
|---|---|---|
| Clear | nothing | about 14 hours (12 real minutes) |
| Cloudy | nothing | about 8 hours |
| Rain | rain 0.45 | about 7 hours |
| Heavy rain | rain 0.9 | about 3 hours |
| Mist | nothing, thick mist banks | about 5 hours |
| Storm | rain 0.8, lightning and thunder | about 2.5 hours |
| Snow | snow 0.45 | about 8 hours |
| Blizzard | snow 0.9 | about 4 hours |
Rain or snow? Whatever falls is snow where the seasonal air at the ground is 0.5 °C or colder, and rain above: a rain over Givre in winter falls as snow, a snow over Cendree as rain.
Getting wet. Rain of 0.3 or more soaks anyone under the open sky with the Wet effect (90 seconds, renewed while it lasts). Any block that stops the rain within 48 blocks over your head keeps you dry. Snow does not soak.
Lightning flashes and thunder come with storms; they are only seen and heard, they strike nothing.
The regions
| Region | Character | Snow |
|---|---|---|
| Mitan | temperate, rain and mist | a little in winter |
| Aube | windy, thunderstorms in summer (a quarter of the time) | a little in winter |
| Vepre | drizzle and fog; its ordinary rain is light (0.25) and does not soak | a little in winter |
| Givre | snow and blizzards, a short rainy summer | from autumn to spring, half the winter |
| Cendree | hot; dry storms (almost no rain) and heavy downpours | none |
| Dents and the sea | wet and windy all year | rare |
Rain waters the fields: an open farmland gets wetter under rain, and does not dry while its ground is frozen (below 0 °C). See Farming.
Mist
Mist banks lie in the valleys, over the water and in the woods. Each region has a mistiness per season (the damp and cold seasons are the misty ones: Vepre and the Mitan in autumn the most, Cendree almost never), and the mist weather is the thickest. The banks thicken at dawn and dusk and thin by midday.
Snow and ice
Snow cover
Snow piles up as 
Snow Layer blocks on every open top surface, one eighth of a
block per layer, eight layers making a whole block.
- It settles below 0 °C: a snowfall of 1 adds 5 layers a day, so a snow (0.45) about 2 layers a day and a blizzard (0.9) about 4.5.
- It melts above 0 °C: half a layer a day per degree, faster under a clear sky by day, and rain melts it too (3 layers a day under a rain of 1).
- The depth is the same for a whole area at the same temperature, so the cover is even, without seams, and the distant terrain whitens too.
- Short plants (tall grass, ferns, flowers, heather, moss, the wild herbs and the mushrooms) are covered by the snow and come back when it melts. Other plants keep the snow off their ground.
- The snowy biomes have their own snow ground, which never melts.
Ice
Still water under the open sky freezes into 
Ice after a few days of cold: each day
below its threshold it has a one in two chance to freeze.
| Water | Freezes below |
|---|---|
| Lake or pond | -2 °C |
| River | -6 °C |
| Sea along the coasts | -10 °C |
| Open sea (no land nearby) | -25 °C |
Above 0.5 °C the ice thaws, with a 70 % chance a day.
The plants through the year
The seasons show on the land (on screen only, the world is the same):
- Grass and plants go from tender green in spring to deep green in summer, russet and brown in autumn and dull straw in winter.
- Deciduous trees turn and lose their leaves, each species in its own way: the birch golden, the rowan bright red, the beech copper, the ash bare first, the willow last, the wild apple in white and pink blossom in early spring. The spruce, pine and yew stay green all year. A bare canopy still stands and still shades.
- Wild plants flower in their seasons and give their fruit or flowers only then:
| Season | Flowering or fruiting |
|---|---|
| Spring | wild garlic, woad, mandrake, moss |
| Summer | bilberry, belladonna, St John’s wort, nettle, mugwort, weld, madder, aconite, water lily, bramble |
| Autumn | bramble (blackberries), cranberry, heather, mistletoe |
| Winter | mistletoe |
What each herb gives is in Herbalism; the crops have their own seasons, frost and dormancy, in Farming.