Zombie Forecast is a feature that is used to gauge zombie behavior during Always Be Looting and Siege events. The forecast reveals three particular details: swarm/seige size, zombie aggression and time of day. Each forecast has various levels of intensity which differs depending on certain parameters.
Swarm Forecast / Siege Forecast
This shows how many zombies to expect to find during the mission. It can vary immensely, and will have an impact on the difficulty. A Siege Forcast is different in that there are much harder difficulties. Exclamation marks affect the difficulty- the more !'s, the more zombies.
A list of all the swarm sizes, from less to more crowded:
Army of Death/!/!!/!!!/!!!!/!!!!!
This shows how irritated the zombies will be, how quickly they'll take notice of you. A low Aggression will let you walk right past a zombie without it trying to attack, while with high enough Aggression, a zombie could notice you from even the far side of your screen. Rain will affect zombie behavior by making them more aggressive.
These are all the Aggressions, from calmest to most annoyed:
DIE!!! (Unknown if implemented)
These are the times of day that your expedition starts out at. This is the most overlooked factor of them all, but it's important- the game tells you to "FEAR THE NIGHT" for a reason. It gets harder to see, and zombies swarm and get quite irritated, no matter what the other forecasts say, when it's 9:00 at night..
Here is a list of the times of day that you can start your mission at. NOTE: This is not EXACT, the exact time of day will vary within half an hour of the time shown here.
Midnight 1:00 AM
Before Dawn 5:00 AM
Daybreak 7:00 AM
Morning 9:00 AM
Late Morning 11:00 AM
Noon 12:00 PM
Near Noon 1:00 PM
Afternoon 2:00 PM
Late Afternoon 5:00 PM
Near Sunset 7:00 PM
Nightfall 9:00 PM
After Dark 10:00 PM
Late Night 12:00 AM
TIME TO BUY A NEW WATCH: Is never explicitly stated, however, it is the darkest setting. It is guaranteed to appear in the Dark Mansion, the Haunted Mansion, and the Spooky Graveyard and also has a chance of appearing in the River of Sludge. It cannot appear in any other mission.
- "Late Night" is actually closer to the time of midnight than "Midnight" itself.
- If the time gets to 9:00 PM on any non-siege mission that started before 9, when the background music's current loop ends, it will fade away and be replaced with "They Can't Be Stopped". This is a reminder that the game is going to send more a few zombies your way, and it is generally a good idea to skedaddle.
- The 1.5 hour penultimate Siege and the Final Siege have pre-determined horde sizes for their forecast, scaling with the game mode, from Massive!!! on Short Trip to Heck Mode to NO HOPE on Marathon Mode and K*E*P*A Mode. The Canada map also has a pre-determined swarm size, from Very Thick!!! on Short Trip to Heck to Impossible on Marathon and K*E*P*A, and the aggression will always be Mega-Cheesed.
- The Kaiju encounter shows Swarm Forecast SOMEWHAT BIG with Aggression SUPER ANNOYED at Current Time MONSTER TIME.