Why iRacing’s Amazing Weather System Is Basically Turned Off

Two years since a team of people spent thousands of hours building what is, objectively, the most advanced meteorological system in sim racing. And two years later, the question remains the same: what on earth did they build it for?

There is a very clear difference between having something and actually using it. iRacing has Tempest. It exists, it works, it’s impressive. But what they do with it is, essentially, leave it sitting in a drawer.

In this first week of the new season, out of every series in the simulator, only one has real dynamic rain options. Just one. And it’s not that the others have a low percentage they have zero. Literally 0%, week after week, season after season.

The F4 a car that handles brilliantly in the wet from day one has four active series. Four. Let’s do the quick maths: roughly 804 races per series over the course of a season. Multiplied by four. That’s over 32,000 consecutive races without a single rain option. Not just this season. Over the entire past year.

The Regional GT3 series, three separate competitions for Asia, Europe and America. Result: none, none, none across the board. The BMW M2, both in its rookie and advanced series, exactly the same. The Rister that series that changes car every week and always visits Mosport has seven rain-tyre-equipped cars available this season: the LMP3, the Skip Barber, the Audi 90 GTO (brand new this season), the GR86, GT3, GT4. Every single one at 0%. Always.

There is, to be fair, one ray of light. The special weekend multiclass series GT4 paired with TCR or GT4 with LMP3 has five of its twelve weeks with rain options, hovering between 28% and 35%. That’s nearly half the season with a genuine possibility of something happening.

And here comes the figure I find most telling: real Formula 1, over the last five years, has seen wet conditions in 15.8% of its races. A number that, as it happens, lines up quite well with what that one well-configured series offers. Coincidence or not, it proves the range is perfectly reasonable. What isn’t reasonable is that it remains the exception rather than the rule.

The Button That Exists and Is Never Pressed

This is the part that frustrates me the most. Because this is not a problem of iRacing not having the solution. They have it. It’s right there in the interface, visible, accessible. It’s called auto, and what it does is exactly what should be done: generate realistic weather conditions based on historical data for each circuit, date and time of year.

I press that button in a hosted session and at Spa in May it might generate a 78% rain chance. I press it again and it returns 0% with clear skies. I press it once more and a bit of late-session rain appears. Every time different. Every time logical. Every time without me being able to predict it in advance.

And what does iRacing do with all of this in its official series? It always uses the same thing: two weeks out of twelve with a fixed 30%, the same percentage, the same weeks, the same setup. The entire week identical. Every Tuesday morning race a carbon copy of the Saturday night race.

The historical weather model per circuit, which they have been building since February 2024, is used for absolutely nothing in the official series. Not at Spa, where it rains with reasonable frequency in spring. Not at Silverstone. Not anywhere. Here’s 25% at Road America in June and 0% at Spa in May. Just the way it goes, apparently.

Some people still see this as a binary question: either it rains or it doesn’t. And that’s exactly where the confusion lies. The value of Tempest isn’t rain itself it’s uncertainty.

When you enter a real race at any level, from karting to F1 you don’t know exactly what the weather will be like when you get on track. You might have a forecast, but not a guarantee. And that uncertainty forces you to prepare, adapt and make real-time decisions. It’s part of the challenge.

In iRacing right now, I know with absolute certainty that next Tuesday’s F4 race at 7:15 will be dry. And Wednesday’s. And Thursday’s. And every race that week. And the week after. And the entire season.

That isn’t sim racing. That’s a video game with locked parameters.

What It Could Be

The system they have built is capable of generating, for every race created, a completely different forecast. One session might have a soaked track from earlier downpours with the surface slowly drying during the race. Another might have threatening clouds that never quite break. Another might be a perfect sunny day. And the session an hour later could be something else entirely.

All of that, for every single race, automatically, without any human intervention, is exactly what would happen if they simply automated what I do when I press that button in a private server.

It isn’t a new system. Nothing needs to be built from scratch. All it takes is for each new race lobby to regenerate its conditions using the historical model that already exists. That’s it. The hard work is already done.

I don’t go by words I go by facts. And the facts are these: two years after launch, iRacing has not only failed to make proper use of Tempest, but has continued adding more cars with wet-weather tyres GTE, several others this past season only to then apply the exact same 0% calendar to them as everyone else.

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There was a development update in November 2025 where they mentioned they were considering the possibility of regenerating conditions between sessions. Fine. When that happens, I’ll be the first to celebrate it. But until then, what I trust is what I see: the button exists, nobody presses it, and 32,000 races later we’re still exactly where we started.

I genuinely hope I’m wrong.