Source: am aerospace engineer, have worked on multiple launch vehicles
Great question, and I think you should do some more investigation into what you actually want to know and why (currently it's not well-posed but I'll try to answer all the questions you could be asking). Keep in mind MaxQ is a load condition, and frankly, engineers don't care so much about temperatures as heat rates (thermal loads). Things can be a lot of different temperatures.
Assuming you're asking only about the ascent portion of the trajectory:
If you're asking about what location on the rocket, that is almost always going to be on the base of the rocket, just above the engine - this is especially a concern for multi-engine stages, such as Saturn V: The heating from expanded rocket plumes impinging on the base is extreme to say the least - check out the Saturn V Base Heating Handbook, 600 pages of some of the coolest engineering you can find (you can also find it just be googling "Saturn V base heating"): https://ntrs.nasa.gov/citations/19720023245
If you're only interested in the body temperature of the vehicle, you have to ask yourself why you're interested in this value - most large vehicles (F9 included) use their tanks as the rocket body, so that would stay approximately as cold as the LOX itself - cryogenic in that case. This differs a lot based on which part of the body you're interested in (fairing, booster body, raceway, etc)
If you're asking about what point on its ascent trajectory (like maxq), the reason there's not an easy answer to that question is because temperatures don't really matter - heat rates matter. Differeny things (metals, composites, etc) heat up at different rates and for different reasons. Overall, it varies based how fast the vehicle moves in which portion of the atmosphere, but it also matters where on the vehicle something is. Peak temps on different parts may happen at different times, the "temperature" of a rocket isn't something that's tracked.
If you're asking about aerodynamic heating on F9 specifically, that definitely happens during reentry:
You can get a much more intuitive understanding of aerodynamic heating by looking at reentry vehicle aerothermal profiles - for example, with a high ballistic coefficient, the peak heat RATE is higher, but the net heat LOAD is lower, whereas this is flipped for a lower ballistic coefficient. This relationship is flipped when it comes to the atmospheric entry angle - how much time you spend at which portion of the atmosphere going at what speed determines heat rate and heat load - two subtly different concepts. This is an awesome resource: https://www.faa.gov/about/office_org/headquarters_offices/avs/offices/aam/cami/library/online_libraries/aerospace_medicine/tutorial/media/iii.4.1.7_returning_from_space.pdf