Weather in ACC is not a visual effect. It moves the track temperature, the grip and the tyre you need, and in a long race it decides the result more often than pace does.
This page covers how the weather system works, how to set it up for practice and how to read it in a race. For the car setup and the driving once it is raining, go to the ACC wet weather guide.
The weather settings
| Setting | What it does | What I would use |
|---|---|---|
| Air temperature | Sets how warm the day is. Track temperature follows it, plus sun and cloud | The temperature of the race you are practising for |
| Cloud level | How much of the sky is covered. More cloud means a cooler track, and rain needs cloud | Low for a hot dry race. High if you want rain to be possible |
| Rain level | How hard it rains. Zero is dry | Zero for dry practice. Medium to learn the wet |
| Variability | How much the weather moves from the values above. Zero keeps it fixed | Zero when you test a setup. Low to medium for race practice |
| Time of day | Sun position, light and track temperature | The race start time |
| Time multiplier | How fast the clock runs. A 24 hour day can pass in one hour | Match the race or league rules |
Rain needs cloud. The weather will not jump from a clear sky to a storm in three minutes. So for a session where rain is possible but not certain, raise the cloud level, keep the rain level low and give it some variability.
For setup work I would always use zero variability. If the track temperature moves between runs, you cannot tell if the car got better or the track did. More on that in the ACC track temperature guide.
Weather on a server
If you run a server or race in a league, the same settings live in the event file. The handbook from Kunos gives the weather randomness as a number from 0 to 7.
| Server value | What you get |
|---|---|
| 0 | Static weather. What the session starts with is what you keep |
| 1 to 4 | Fairly realistic changes around the base values |
| 5 to 7 | Big swings. Kunos calls these more sensational |
In a public lobby or league race, check the session info before you join. If the randomness is above zero, bring a wet setup. The ACC multiplayer guide covers the rest of the server side.
Reading the forecast
ACC gives you a weather widget on the HUD. It shows the conditions now and the forecast for 10 and 30 minutes ahead. If you do not see it, turn it on in the HUD options. The ACC HUD guide goes through the widgets.
A few things to know about it:
- It is a forecast. With high variability it can change its mind. Look again every few laps.
- Clouds come first. When the sky fills in and the track temperature drops, rain is close.
- The track state is the real answer. Greasy, Damp, Wet and Flooded tell you what the tyres are standing on right now.
- Other cars are data. If a car that just pitted for wets is much faster than you, the question is answered.
How a shower plays out
The track does not go wet the moment it rains, and it does not go dry the moment it stops. That lag is where races are won.
When the rain starts, the first minutes are Greasy. Slicks still work if you are careful. Then it goes Damp, then Wet, and now slicks are finished.
When the rain stops, the track stays wet for a while. A dry line appears where the cars drive. Off line it is still wet, so passing is risky. And do not expect the grip you had before the shower on the first dry laps.
The pit calls
| Situation | The call |
|---|---|
| Dry now, rain in 10 minutes, pit window open | Do the mandatory stop when the rain arrives and take wets. One stop instead of two |
| Dry now, rain in 30 minutes | Do nothing yet. Check the forecast again every few laps |
| Greasy, forecast says it passes | Stay on slicks. Brake earlier and stay off the rubber line |
| Wet, forecast says it stops soon | Stay on wets until a dry line shows. Cool them in the wet patches |
| Damp and drying, other cars on slicks are faster | Box for slicks now |
| Night and rain together | Leave more margin. You cannot see the puddles |
The costly mistake is the double stop: you pit for fuel on lap 20 and again for wets on lap 23. If rain is in the 10 minute forecast and your pit window is open, wait for it and do both in one stop.
Set the tyres and pressures in the pit menu before you reach the pit lane. Wets want 30.0 to 31.0 psi hot. How to work the menu is in the ACC pit stop guide, and the wider planning is in ACC race strategy tips.
Night and rain
Night on its own is fine. The track is cooler and often quick. Night with rain is the hardest condition in the game. The spray lights up in your headlights, you cannot see the puddles and the braking boards disappear.
Slow down more than you think you need to. Use the lights of the car ahead as your reference for where the track goes. And practise it once before you meet it in a race.
How to practise weather
Three sessions, 20 minutes each:
- Fixed wet. Rain at medium, variability zero. Learn the wet line and the puddles.
- Rain arriving. High cloud, low rain, some variability. Practise the call to pit.
- Drying track. Start on a wet track with the rain off. Learn when slicks start to work.
After those you know more about ACC weather than most of the grid.
FAQ
How do I check the weather forecast in ACC?
Use the weather widget on the HUD. It shows the weather now and the forecast for 10 and 30 minutes ahead.
How do I make it rain in ACC?
In the weather settings, raise the cloud level and the rain level. For fixed rain, set the variability to zero.
What does weather variability do in ACC?
It sets how much the weather changes during the session. Zero keeps it fixed. Higher values let cloud, rain and temperature move.
Can I set rain to start at a certain time in ACC?
No. You cannot script it to the minute. You can only make it likely with high cloud and some variability.
When should I pit for wet tyres in ACC?
When the track state reaches Wet, or earlier if the forecast is sure and your pit window is open. On a Greasy track, slicks still work.
Does weather change the track temperature in ACC?
Yes. Cloud cools the track and sun heats it, so the tyre pressures move with the weather even when it stays dry.
What is the hardest weather in ACC?
Heavy rain at night. Grip and visibility are both low, and standing water is hard to see.