Real Road has some issues with too cold temps i think or maybe Real weather needs some small fixing with the new build. Race was at Highland Motosport Park
If the race date is set in the summer, then it takes temperature from that time. The game takes location of the track, date of the race, time of day, cloudiness and ambient temperature to determine the track temperature. If the track is set in the middle of summer and you put 0 degrees while it's sunny and daytime the track won't be close to 0°C.