A weather reroll in iRacing means the forecast for an official series gets generated again. Before, one forecast covered a whole race week. With rerolls, the weather is regenerated once per race day or for every single race, so two races on the same car and track can run in different conditions. iRacing introduced the name in September 2026 and is testing it in Season 4.
Checked on 15 October 2026 against iRacing's Development Update for February 2024 (13 February 2024) and August 2026 (28 August 2026), the 2026 Season 3 Week 13 announcement (5 September 2026), the 2024 Season 2 Patch 1 notes for build 2024.03.13.01 and Patch 1 Hotfix 2 notes for 2024.03.20.02, the 2026 Season 4 Initial Release Notes for build 2026.09.09.01 and the iRacing weather page, all on iracing.com and support.iracing.com. Where iRacing has not published something, I say so instead of filling the gap.
Is "weather reroll" an official iRacing term?
Yes. iRacing uses the word itself.
iRacing's own Week 13 announcement on 5 September 2026 introduced an "all-new Weather Reroll" to mix up the conditions more often. The August 2026 Development Update uses the same idea and says Season 4 tests "weather re-rolls" in two ways: per-race and per-race-day.
So when someone in the grid chat says the weather rerolled, they mean the series generated a fresh forecast for that race or that day.
How official series picked weather before rerolls
To understand the change, you need the old rule. iRacing spelled it out in the 2024 Season 2 Patch 1 notes (build 2024.03.13.01).
- Each official series used one weather forecast for each race week.
- That forecast was listed in the Race Schedule.
- It was only a forecast. The real weather in the session could shift, so the 9:00 session and the 11:00 session could play out differently.
- Every split launched at the same time got an identical weather progression. All the 9:00 splits had the same weather.
The same patch fixed a bug where every official session in a week had exactly the same weather progression in Forecasted Weather mode. That bug is a good reminder of what the system is meant to do. The forecast is the plan. The sim then plays the weather out with some variation.
What a reroll changes
A reroll moves the point where the forecast is generated.
| Model | When the forecast is generated | Official source |
|---|---|---|
| Weekly (the default since 2024) | Once per race week | 2024 Season 2 Patch 1 notes |
| Per race day | Once per day, at 00:00 GMT in the Week 13 test | Week 13 announcement, 5 Sep 2026 |
| Per race | For every race session | Week 13 announcement and August 2026 Development Update |
In practice, a per-race reroll means you cannot learn the week's weather on Tuesday and assume Saturday is the same. Temperature, cloud, wind and rain can all be different the next time you join.
iRacing has not published exactly when in the session cycle a per-race forecast is created (at registration, at session launch or somewhere else). I would not build a plan around a guess on that.
Where iRacing has tested rerolls
The first public test was the 2026 Season 3 Week 13 series, announced on 5 September 2026:
| Week 13 series | Reroll setting |
|---|---|
| Ferrari 296 Challenge and GT3 Challenge, Fixed | Once per day at 00:00 GMT |
| Porsche Cup Series | For every race |
For Season 4, the August 2026 Development Update says two things. Rerolls are tested per race and per race day. And iRacing is working with community managers in a few select series to test forecasts with a higher chance of rain. It also says the team is not ready for dramatic service-wide changes yet.
Sim racing press (BoxThisLap and simRacer.es) report that 34 official Sports Car and Formula Car series reroll per race in Season 4, and that selected Class D series keep rain limited to two weeks of the season. I could not find that list or the two-week rule on iracing.com, in the Season 4 release notes or on support.iracing.com. Treat it as reported, and check your own series in the Race Schedule before you rely on it.
The 2026 Season 4 Initial Release Notes (build 2026.09.09.01) do not mention rerolls at all. They cover rain for three new cars (the Aston Martin Valkyrie AMR-LMH and both Caterhams) and new rain particle and mist effects.
How rain chance works in iRacing
Rerolls only change when the dice are thrown. The rules for rain itself are the same as before.
- Three weather modes. Static, Forecasted and Timeline. To have falling rain, the session must use Forecasted Weather. Static can give you a wet track, but not rain falling.
- Track and car. Rain needs an asphalt road course and a rain-enabled car.
- Series admins decide. iRacing's February 2024 Development Update says rain is enabled series by series, and only in select weeks.
- Historical data. The same update says the forecast is dynamic and tied to historical weather at each track.
- Capped intensity. In March 2024 (build 2024.03.20.02) iRacing reduced the maximum rain rate in official sessions slightly, so they stay drivable.
- Longer races, more uncertainty. iRacing says this directly. A 40 minute sprint is easier to predict than a 6 hour race.
A rain chance in the forecast is a probability. Even with a high number, a rerolled race can stay dry, and a low number can still bring a shower. In real racing I never trusted a forecast as a promise either. You read it, you plan for the likely case and you keep a plan for the other one.
In hosted sessions you control this yourself. In Forecasted mode you set the chance of rain and when it is allowed, and the Regenerate button produces a different forecast. That button is the reroll you can press by hand.
What you can see before and during a race
| Where | What it shows |
|---|---|
| Race Schedule | The weekly forecast for series that still use one forecast per week |
| In-sim weather tab | Current radar and a forecast for the next several hours |
| Weather black box on the driving screen | A near-future forecast |
| Spotter | Radio updates on weather changes, and you can ask for one |
For rerolled series, the weekly forecast in the Race Schedule cannot describe every race any more, because each race gets its own. iRacing has not published how the schedule display handles this. So the in-sim weather tab and the weather black box in the session are what count.
How I would prepare for a rerolled week
The skill that matters now is reacting, not memorising one forecast.
- Build two setups in open setup series. One dry, one for a damp or wet track. If you only run fixed series, you skip this, and my guide to fixed vs open setup series explains what you can and cannot change.
- Check the weather tab every time you load in. Do not rely on what you saw in yesterday's race. iRacing has not said whether practice, qualifying and the race share one rerolled forecast, so look again before the start.
- Know your tyre call. iRacing tracks whether the race has been declared wet, which is when the marshal allows rain tyres. Your crew chief and spotter help, but picking the wrong tyres at the start is on you.
- Get the dry tyres in the window fast. A cool, cloudy reroll means a longer warm-up. My notes on heating up tyres in iRacing and on iRacing tyre pressures apply directly.
- Plan the pit call before the rain arrives. In longer races the switch to wets wins or loses the race. How to make pit decisions in iRacing covers the thinking.
- Practise wet driving offline. iRacing itself recommends a Test session or AI race first. In the wet, the grip is off the dry line. Look for it.
Why iRacing is doing this
The August 2026 Development Update says iRacing has been watching feedback on its dynamic weather and rain system since it launched. Rerolls and higher rain chances in a few series are meant to collect data and see how drivers react.
The same update says the longer-term plan is more condition variability, more life-like weather patterns and a wider atmospheric simulation. No dates were given.
My view: rerolls are good for racing. One forecast per week rewards whoever ran the most laps on Tuesday. A fresh forecast every race rewards whoever reads the conditions best on the day, and that is closer to real motorsport.
FAQ
What is a weather reroll in iRacing?
It is when an official series generates a new weather forecast for each race day or each race, instead of one forecast for the whole week. iRacing introduced the term in September 2026.
Do all iRacing official series reroll the weather?
No. iRacing calls it a targeted test in Season 4. Press reports say 34 Sports Car and Formula Car series reroll per race, but iRacing has not published that list on its own site that I could find. Check your series in the Race Schedule.
How often does the weather reroll?
It depends on the series. In the Week 13 test, the Ferrari 296 Challenge and GT3 Challenge rerolled once per day at 00:00 GMT, and the Porsche Cup rerolled for every race.
Does a high rain chance mean it will rain?
No. The forecast is a prediction. The real weather can drift during the session, and a rerolled race with a high rain chance can still stay dry.
Where can I see the iRacing weather forecast?
In the in-sim weather tab (radar plus a forecast for the next several hours), the weather black box on the driving screen, and from your spotter. Series with a weekly forecast also show it in the Race Schedule.
Can it rain on every track in iRacing?
No. Falling rain needs Forecasted Weather mode, an asphalt road course and a rain-enabled car. Ovals and dirt tracks do not get rain.
Can I reroll the weather in a hosted session?
Yes. In Forecasted Weather mode, the Regenerate button creates a different forecast. You also set the chance of rain and when rain is allowed.