MechWarrior 5: Mercenaries
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About this mod

Despite occasional lancemate dialogue to the contrary, mission environment in vanilla MW5 does not affect heat dissipation. The mission climate will now change how quickly heat dissipates for all mechs. This is a beta release as it needs fine tuning, looking forward to feedback! @Sketch on the official MW5 discord channel

Permissions and credits
Note: As of version 1.0, Biome Heat Effects requires the MW5 Mod Compatibility Pak.  Also note that cooling modifiers will be disabled when running the Mercs Reloaded mod to prevent modifier stacking, though the debug widget ("\" key) will still show the effective cooling rate under that mod's modifiers.


Cold and hot climates, time of day and atmospheric pressure now contribute to how quickly heat dissipates for all mechs on the map.

Post-May 19 game update
A few things have changed:
  • PGI removed atmospheric pressure from their scenario generation outcomes pending a future release.  Atmospheric pressure is now a random outcome based on upper and lower bounds for each biome.  See details below.
  • Biome and atmospheric pressures are now combined for a single cooling modifier using the aforementioned bounds to balance the impact of extreme biomes (e.g. Glacial Ice, Volcanic)
  • Weather modifiers have been introduced that give cooling modifiers for heavy and extreme precipitation and particulate (Rain, Snow, Caustic Rain and Ash).  These will only apply if you are running Raining Fire's Weather Improvement Mod.  Why?  Because vanilla weather is too weak to warrant cooling modifiers. :)

Plug in the mod and go!  If a co-op host is running this mod, all clients will have their heat dissipation modified as well regardless if they have the mod installed.

While PGI will be releasing their own version of climate heat effects at some point in the future, it is not yet clear when that will be.  This mod is meant to make gameplay feel a bit more realistic in the meantime (and who knows, may inform PGI's implementation!). 

Cooling modifiers:
Cooling modifiers are multiplied by the mech's heat sink configuration to get the effective heat dissipation rate for the mission.  Any modifier greater than 1 increases heat dissipation and vice versa (1.05 means a 5% increase in cooling, 0.95 means a 5% decrease).  All biomes with vegetation are now restricted to atmospheric pressures of high, normal or low.

Full Cooling Modifier Details (Google Sheets)

The highest and lowest modifiers you will see in a given biome: 

Moolamu for the sweet Stone Rhino artwork:
Thanks to NightDustDragon, Seitan and qe2eqe for their help in testing and fixing co-op!
Thanks to LtSnoWolf and cohorts for troubleshooting a serious bug in v1.01!