The thousands of pilgrims who made their way to a storm-battered province in Central Philippines to gain a glimpse of Pope Francis will never forget during his four-day pastoral visit last month.

Soon after he got back to the Vatican, Francis wrote a letter to Palo Archbishop John Du to thank him for his hospitality during his visit in January to this strongly Catholic southeast Asian nation.

The Pope also expressed his amazement of the turnout of pilgrims, who headed to Tacloban City where the pontiff celebrated Mass and broke bread with typhoon survivors.

The letter, which the archdiocese revealed on Tuesday to members of the media in the Philippines, was passed on through social media websites.

"I wish to convey with these words my profound gratitude for your hospitality in the Archdiocese of Palo," the Pope wrote in the one-page letter with his papal coat of arms on the upper part of the stationery. He signed it "Francis."

"I thank you, wholeheartedly, for this witness of faith and endurance which your people showed me in the midst of their trials," he continued. "I will never forget this - may the Lord never permit me to - and I will keep them in my prayers."

He lamented that the circumstances of wild weather during his visit forced him to cut short his trip in the city, which bore the brunt of the Typhoon Haiyan in 2013, one of the strongest storms to hit the Philippines in recent memory.

Thousands of people died in Tacloban and elsewhere, with some seeing their entire families wiped out in one fell swoop. The typhoon likewise destroyed homes, agricultural lands and other facilities.

Francis also apologized for his shortcomings during the event.

"I was deeply saddened that the weather warning forced us to anticipate our departure by four hours; this prevented a more relaxed visit with your people and in the cathedral later that afternoon," the Pope wrote in the letter. "I ask forgiveness for any impatience on my part at that time."