When revelation descended upon Messenger of Allah ﷺ even during the cold days, his forehead perspired. (Using translation from Muslim 2333a)
إِنْ كَانَ لَيَنْزِلُ عَلَى رَسُولِ اللهِ ﷺ فِي الْغَدَاةِ الْبَارِدَةِ فَتَفِيضُ جَبْهَتُهُ عَرَقًا عَلَيْهِ الصَّلَاةُ وَالسَّلَامُ