One of my friends works as mason. He was keeping fast this Ramadan also but one day due to extreme heat, humidity and heavy work load he could not bear the fast and had to end the fast during noon. Now, he will have to make qaza only or qaza and kaffarah both?
بسم الله الرحمن الرحيم
(Fatwa: 1439/B-329/TB=11/1434)
If your friend broke the fast due to extreme hunger and thirst then only qaza is wajib on him not the kaffarah.
قال الشرنبلالى: صائم أتعب نفسه فى عمل حتى اجهده العطش ، فأفطر لزمته الكفارة وقيل لا ، وبه أفتى بالبقالى. (رد المحتار 3/401 ط زكريا)
Allah knows Best!
Darul Ifta,
Darul Uloom Deoband