«كان إذا اشتد البرد بكر بالصلاة وإذا اشتد الحر أبرد بالصلاة»
It was the practice of the Prophet (peace and blessings be upon him):
"When the cold was severe, he (peace and blessings be upon him) would pray the prayer early, and when the heat was severe, he would delay the prayer (until it was cooler)."
Hadith Referenceصحیح الجامع الصغیر / حرف الكاف / 4669