​ Baseline weather with no modifiers. Just enjoy the sun bro

Harder to detect enemy air and navies.

Airplane attacks against ships less effective as well as ship-to-ship accuracy.

Higher risk of airplane accidents.​

A much stronger version of Light Rain.

Carrier planes won't be able to take off.

Bombers will have a hard time hitting targets.​

Harder to detect enemy air and navies.

Airplane attacks against ships less effective as well as ship-to-ship accuracy.

Higher risk of airplane accidents.​

A much stronger version of Snow.

Carrier planes won't be able to take off.

Bombers will have a hard time hitting targets.​

Almost impossible to detect other aircraft.

Extremely high chance of airplane accidents.

Bombers won’t be able to hit targets on ground.​

Big thunder storm over Russia (sorry I did not have the reflexes to be able to catch the lightning )

Baseline terrain, so no modifiers, as everything is relative to this.​

50% added to time to move through.

20% penalty to attack.

20% smaller combat width.

10% better protection against enemy air superiority.​

50% added to time to move through.

20% penalty to attack.

33% smaller combat width

5% better protection against enemy air superiority.​

100% added to time to move through.

40% extra attrition

66% smaller combat with

40% penalty to attack

10% better protection against enemy air superiority.​

20% added to time to move through.

30% penalty to attack​

50% added to time to move through.

50% extra attrition

25% smaller combat with

30% penalty to attack

25% better protection against enemy air superiority.​

100% added to time to move through.

80% extra attrition

25% smaller combat with

40% penalty to attack​

5% added to time to move through.

30% extra attrition​

Hello, and welcome to the 28th development-diary for Hearts of Iron IV. This time we talk about the things that you have the absolutely least control over in the game, and in real life. ie, Weather and Terrain.We were not happy with the weather-system in HoI3. It was a complex simulation that tried to work as close to reality as possible. It was basically impossible to tweak to the situations we wanted (like very hot desert areas or cold winter in Russia in ’41), and players disliked it. It was a small performance hog and last but not least - all that effort was tucked away in a mapmode you had to keep checking (so most people did not). So for this iteration of the series, we decided to take an entirely different approach.Probability for each type of weather can now be scripted for each strategic region for each month, or a definable period. So for example we can get that hardcore, dirty, Russian mud everyone is craving for the months and locations where it makes sense. For modders out there we made a really nifty tool for setting up these values so its easy to tweak and work with (so when you guys make the Cats of the 4th Reich total conversion I’v been waiting for it will be easy). This means that since we can set everything ourselves we have full control over the gameplay effects we want rather than relying on a complex simulation to get it right.There are 6 types of basic weather in the game. These directly affect air and navies and land units indirectly (we get to that)Clear skiesLight RainStormSnowBlizzardSandstormTemperature is tracked on province level and mainly affects attrition levels. If its very cold or very warm things will tend to break down a lot more often. You’ll want leaders with the Winter Specialist trait to maximize your efficiency in cold weather.When it rains or snows we keep track of that (so we can show it on the map) but also to keep track of if it has gotten to extreme levels. Very high snow will affect unit movement speed, but Mud is going to increase attrition levels a lot as well as slow you down to a crawl. A smart player will try not to attack (as a wild example) The Soviet Union just as mud season begins or they might find a lot of their panzer divisions bogged down.Since weather has such a large impact we wanted to make sure it was always visible to the player. Snow/mud and such is shown directly on the map while storm clouds and rain is in a layer above which we fade away the closer you get so as not to obscure unit movements.While we do quite a lot of things at the state-level, we still have terrain defined per actual province. The terrain-system is completely scriptable as in all Clausewitz games, but the terrains in Hearts of Iron IV is as follows.PlainsForestHillsMountainsUrbanJungleMarshDesertDifferent types of battalions have either penalties or bonuses in terrain to attack, defence or movement, compared to a generic Infantry. A few examples. Cavalry has a minor -5% attack penalty in most rough terrain, while Mountaineers gets a movement bonus in hills & mountains, as well as attack and defence bonuses.Unit-specific penalties that combine negatively with terrain penalties, creates some pretty bad situations. ie, attacking a mountain with heavy armor is NOT a good idea.Next week, we’ll look at factions, and wargoals!