TerraLib
by justElias
TerraLib is a Fabric library that adds seasons, per-player temperature and namespaced world-saved data for other mods to build on.
What it does
Seasons cycle through Spring, Summer, Autumn and Winter as days pass, and a season-changed event lets other mods react when the transition happens. A day-changed event fires at each new day, so mods can run logic on a daily schedule without tracking time themselves.
Temperature is simulated for each player separately. The library ships with built-in effects for freezing and overheating, and a player-temperature-changed event notifies dependent mods when the value moves. Namespaced NBT storage writes data straight into the world files, so mods can keep their own state without a separate save system.
The library requires Fabric API and is released under the MIT License. A server running it needs every connecting player to have it too. Builds cover only 1.21.1, with 1.0.0 as the latest file, published 2026-05-06.
Key features
Season tracking
Days move through Spring, Summer, Autumn and Winter, with an API that exposes the current season to other mods.
Per-player temperature
Each player has a temperature value that can cause freezing or overheating effects, which mods can read or extend.
Namespaced world storage
Data is stored under a namespace in the world files, keeping each mod's values separate from the others.
Season, day and temperature events
Hooks fire when the season changes, when a new day begins and when a player's temperature changes.
Compatibility
Latest build for each game version and loader.
Only full game releases are shown. This mod publishes no snapshot builds.
Use cases
Seasonal survival mods
Mods that change crops, mobs or weather by season can read the current season instead of building their own clock.
Temperature-based gameplay
Survival mods can attach clothing, shelter or biome effects to the temperature value the library already tracks.
Who it’s for: Mod developers building seasonal or temperature mechanics, and server owners who run those mods on Fabric 1.21.1 with the same environment on both sides.
How it compares
Temperature API is a Fabric library for the same temperature idea, covering 1.20.1 – 1.21.11 under the MIT License and running on client and server. Seasons API covers 1.21 – 1.21.5 under the Apache License 2.0 and is optional on either side. Blooming Seasons is server-side only for 1.20.1 and is not open source, so players join without it. Madoku Craft: Core runs on client and server for 1.21.1 – 26.3 under the GNU Lesser General Public License v3.0 only.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| TerraLib | Fabric | 1.21.1 | Client and server | 2026-05-06 |
| Temperature API | Fabric | 1.20.1 – 1.21.11 | Client and server | 2026-06-12 |
| Seasons API | Fabric | 1.21 – 1.21.5 | Client or server, optional | 2025-05-04 |
| Blooming Seasons | Fabric | 1.20.1 | Server-side only | 2025-05-02 |
| Madoku Craft: Core | Fabric | 1.21.1 – 26.3 | Client and server | 2026-10-13 |
Questions
Does TerraLib need Fabric API?
Does the server need TerraLib installed?
Which versions does TerraLib support?
In the catalog
TerraLib is one of 3,514 Library mods on ModsFinder, and one of 2,348 Library mods for Fabric. 32,366 mods support Minecraft 1.21.1.
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What the author says
A lightweight Fabric utility library for seasons, temperature, and world-persistent data. Designed to power seasonal survival mechanics with ease.
Official listing
- Modrinth page
- modrinth.com/mod/terralib
- Owner
- justElias
- Published
- 2026-05-05
- Updated on Modrinth
- 2026-05-06
- Facts verified
- 2026-10-15