Seeing as how: `` “message” : “Unsupported parameter: ‘temperature’ is not supported with this model.” ``` is now a thing with GPT-5 models (as they’re reasoning models) - how does that work when it might get handed off to a “non-thinking” model (as is done in ChatGPT)? Or is this just not a thi…

Is it because of maintaining a stable reasoning? Will they add the ability of temperature being a parameter in the future?

Will they add the ability of temperature being a parameter in the future? Don’t count on it. Temperature and top_p parms are not needed for GPT-5 models.

This is a breaking change and absolutely unexpected, I really hope the add it as a significant number of real-world applications rely on more deterministic responses.

I am facing the same issue! But it works with the default value of 1.0 but no option to vary it. Does anyone else experience the same?

[image] randompapaya: But it works with the default value of 1.0 but no option to vary it. Does anyone else experience the same? You experience the same behavior with other API reasoning models and attempts at top_p or temperature. You can send the defaults=1 successfully. Divergence from th…

I’m using GPT-4.1 for RP/world-building, and the “temperature” parameter has been very important for the quality of output. It even took a while to figure out the right “temperature” for each project. It’s such a big parameter that I find it odd that there’s no mention of it in the docs related to G…

This is extremely annoying but what I found even more annoying is how OpenAI does not have a proper way for developers to give feedback about API issues like this one.

This was a bit of a surprise. I was unable. to find the fact that temp and top-p are not available for the GPT-5 series of models in the docs, which threw the update of my code. Working in healthcare setting, this is somewhat of a concern as locking down variability of responses is a valuable contro…

After some digging and testing, I realized that GPT-5 does not support “temperature” at all, and it performs awfully at storytelling. However, GPT-5-chat-latest does support “temperature” and does better at storytelling but is not as intelligent as GPT-4.1 (GPT-5-chat-latest says a few dumb things t…

Temperature in GPT-5 models

API

Zellectronic August 7, 2025, 7:51pm 2

Yes, just ran into this myself. My guess is “this is just not a thing anymore,” but perhaps we’ll see.

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Temperature in GPT-5 models

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