The Heatmap is a mechanic that controls the spawn of Zombies depending on the player's activities. It does not have a literal implication towards temperature but it does affect a certain area around the affected zone. It may be easier to think of this as a measurement of the activity level in a given area. The higher the activity level, the more likely zombies will appear.
Every chunk (16 x 16 block area) has a heat level value and various activities can increase the heat level. Heat generated in a chunk affects that chunk and all adjacent chunks. Once the heat-generating activity stops, the heat level will decrease slowly over time.
To see the heat level of the chunk that the player is in, activate debug mode, and press F8.
Effects of Heatmap
If the player performs certain activities in a small area, the heat of that area will increase. If the heat level is high enough, there is a chance that it will be set to around half of it's value and a certain event will happen near the affected zone. The higher the heat of an area the more likely that such an event will happen. 100 points will instantly reset the counter.
Formerly done by the Spider Zombie, scouting is now performed by Screamer, which after spawning, will wander around the affected area. If they spot a player in the area they will emit screams, which will then spawn random zombies around it, possibly even a horde if the screamers are not defeated fast enough.
Even if the screamer does not notice the player, it's always preferable to dispose of it quickly, because it will start summoning zombies by itself when it has scouted for too long and has deiced to storm the player's heatmap-generating object instead.
Pitstop hordes are similar to a wandering horde, but these only happen if the heatmap got reset too many times. Pitstop horde has varied difficulty and is dependent on the reset frequency and may even spawn Special Infected that may cause trouble for the player. Unlike the Wandering horde, pitstop horde will walk directly toward the source of the heatmap, and will eventually seek to break the player's door and destroy the source whether it's the player's campfire, workbench, chemistry station, or much more. Pitstop horde event will never happen during the Blood Moon, and they will never include a screamer.
Things that Affect Heatmap
Using the following items will generate heat.
Note: If you are looking to purposefully generate as much heat as possible, and draw the maximum amount of zombies to a specified area, then 25 campfires fully loaded with wood will consistently reach, and maintain the heat map at 100%, drawing extremely large amounts of zombies, once it reaches 100% you can turn 5 of them off, as you will no longer need the additional boost to maintain the heatmap at 100%. Note: This is also very likely to be changed at some point in the future, making too much activity draw full on hordes to the player's area.
|Name||Heat Map Strength||Heat Map Time||Frequency|
|Ak-47 Assault Rifle||0.3||120|
|Air Filter Land Mine||5||120|
|Cooking Pot Mine||5||120|
|Hub Cap Mine||5||120|