However, there appears to be another error, as Wikipedia also lists the storm as being the deadliest on record in the Philippines, with a death toll of 20,000. I have one source I found that loosely backs it up - from 2014, The Philippines’ Typhoon Alley: The Historic Bagyos of the Philippines and Their Impact. It writes:
The deadliest tropical cyclone on record to hit the Philippines was believed during September 1881. Known as the Haiphong typhoon, the disturbance hit Central Luzon was estimated to have killed up to 20,000 people as it passed over the country September 27, 1881.
I think this death toll of 20,000 is a misrepresentation of a USAID source from 1979 - https://pdf.usaid.gov/pdf_docs/PNAAY550.pdf - which writes:
September 27-October 6 typhoon moved WNW through Camarines, Tayabas and Batangas, causing much destruction; 20,000 killed in Tonking in same storm from high wave
In this source, Tonking refers to the region of northern Vietnam. So I'm a bit stuck. I emailed PAGASA, but they didn't get back to me. I opened up a discussion on Wikipedia, but there hasn't been much interest. Does anyone know if there was a particularly deadly typhoon in September 1881 in the Philippines? I have the storm listed in Wikipedia's article on https://en.wikipedia.org/wiki/List_of_the_deadliest_tropical_cyclones - but I didn't want to add the 20,000, because I don't know if that was the case. I have references to other deadly Philippine typhoons before 1900, but none with a death toll greater than Haiyan in 2013, which appears to be the real deadliest storm in the Philippines.