Lewis Hamilton states the rain that may come during qualifying and the race this weekend will make Friday practice a "waste of a day".
Hamilton ended both Friday sessions in third place, and was one and a half tenths behind Charles Leclerc after FP2.
With air temperatures in the high 30s during the afternoon at Hockenheim, it is expected to be much cooler for the remainder of the weekend, with rain predicted for Saturday and Sunday.
"If it's going to rain for the rest of the weekend then this was a waste of a day," Hamilton said. "I don't feel like we learned much today anyway. It's so hot, nothing from today really applies.
"The tyre will come back towards us and tomorrow we'll be quicker a more comfortable."
Hamilton stated that he struggled with the tyres during the day, having overheating issues throughout the two sessions.
However, the five-time world champion took solace in the fact that everyone else was suffering from the same problems as it was.
"It's not been the best of days in terms of the heat, these tyres don't like the temperatures. So really slow out laps and they don't last very long after that.
"It's just about trying to get the tyres within the working range, they're always above the working range or overheating. That was the main issue today but everyone was in the same boat.
Speaking about the impact of Mercedes' new cooling upgrades after two 90-minute sessions, Hamilton said: "That I don't know.
"We've not had any problems today but we've not been in the race scenario. We did the long runs and I think they were okay, but we're hoping the weather is not like this for the rest of the weekend."