Winter is coming to Nauvis. Prepare your power grid, secure your water supply, and keep the factory warm.

Before installing

Back up your save. Safe removal is not supported yet. The mod replaces terrain tiles and supported buildings with seasonal variants, including in summer. Disabling or removing the mod deletes those variants; the original terrain and buildings are not restored automatically. Your save may become unplayable.

What changes

• Mild winter: water stays open, radars need heating, and unheated production becomes less efficient.
• Cold winter: water freezes, laboratories and long-handed inserters need heating. Offshore pumps need a heated intake or an opening in the ice.
• Severe winter: lakes freeze solid, radars and laboratories need heating, and offshore pumps stop even when heated. Stockpile water, steam and fuel beforehand.

Winter production penalties become stronger in harsher winters. Heating removes those penalties from supported machines. Each winter has its own set of buildings that require heating.

Frozen lakes become both a problem and an opportunity: water access changes, ice can be mined and melted, and frozen surfaces open temporary routes and building space.

A compact forecast appears during the final hour before the seasonal front arrives.

Keep the factory warm

You can power through the cold or build a central heating network to keep production running efficiently and critical parts of your factory warm.

Heating can be more economical than running a cold factory. Winter speed penalties, energy consumption and heating costs are configurable.

Heat pipes can also thaw nearby ground and paving during winter. Original terrain and flooring are preserved, including tiles added by other mods.

Highlights

• Build on frozen water at your own risk: players and enemies can cross the ice, but structures built on it are lost when it melts.
• Mine frozen lakes like pavement: each ice tile yields 🧊10 ice and opens access to the water beneath for offshore pumps
• Fish cannot be caught beneath the ice: make a hole in the ice to catch fish🎣
• Melt ice into water early: the recipe unlocks with oil processing and runs in chemical plants
• Use it before it melts away: stored ice disappears after 20 minutes by default. Freezer can preserve it

How it works

A snow front moves across Nauvis, changing the terrain and applying winter effects as it passes. In summer, a thaw front moves back, restoring the original terrain and removing winter penalties. Buildings on ice are destroyed when it melts. Seasons follow an introductory schedule before becoming random; season lengths and front speed are configurable.

Admin commands:
- /wic-next-season-in-minutes 1 — bring the next season forward to test the mod.
- /wic-start-season <season> [duration_minutes]— start a chosen season: summer, winter1, winter2 or winter3.

Compatibility

Requires Factorio 2.1.21 or newer and Space Age.

Supports:
- Dynamic Rain - rain and thunderstorms stop during winter
- Alien Biomes
- Cargo Ships
- Wood Walls and floors / Lignumis
- Dredgeworks
- Freezer
- Early Heating
- AAI Vehicles: Ironclad
- Dirt Path

For mod developers

Winter tile selection works like this:

1. hardcoded mappings, for special cases like water -> ice and vanilla dirt/grass -> snow variants
2. frozen-<tile-name>, if such a tile prototype exists
3. fallback to snow-flat

So if another mod provides a tile called glass, and also provides frozen-glass, it should automatically use frozen-glass as the winter display tile. If no frozen variant exists, it falls back to snow-flat.

For compatibility, the important part is that terrain-changing mods raise tile-change events when they modify terrain:

surface.set_tiles(tiles, nil, nil, nil, true) -- Set the fifth argument, raise_event = true. This lets Winter Is Coming update its stored terrain and apply winter tiles where needed.

How did your factory survive the winter? Share your observations, bug reports, balance feedback, and gameplay ideas.