Question about track temperature calculation with historical date

So recently I was trying trying to do a 24h Le Mans before the race would actually happen, with the race date set in the future. Having no real weather available, I defaulted to the presets, and I noticed that even selecting any of the cloudy presets on the 14th of June, the temps would be very weird: around 24°C air and 52-54°C track temp regardless of being at 8am or 4pm, and thus sun exposure.
After the real Le Mans I used real weather and for the same weather type and air temperature the track was only 34°C, almost 20°C difference.
So here comes my question, is it maybe a slight bug in the calculations (How is the track temp determined?), or should I stick to real, historic weather? The high track temp make correct setup building quite hard, as it overheats the tires, even the hards on some tracks with fully open brake ducts and no toe.