Since 1981, American weather satellites and a lot of floating instruments have between them measured the temperature of the sea surface, everywhere, every month.
The result is free to download and belongs to nobody. So I took the part covering the Philippines: a grid of squares about 28 kilometres across, 540 months deep. 1,641,600 numbers.
All Of It Is Warming
Of the 3,456 squares in that box, 416 are land. The remaining 3,040 are sea.
Every single one of them is getting warmer. Not most. All 3,040.
The average is +0.23°C every ten years, which adds up to 1.02°C across the record. The fastest square is warming at +0.43°C a decade; the slowest, +0.14°C.
A Degree Sounds Small
It does, so here is the same fact counted a way you can feel.
Take the years 1982 to 2011 and, for each month of the calendar, find the temperature that only the warmest one year in ten beat. Call a month "warm" if it beats that.
By definition that happened about 1.2 times a year back then — 36 months across thirty years.
Over the last ten years it has happened 8.3 times a year.
In 2024, 11 of the twelve months qualified. The thing that used to happen once a year now happens most months.
Put another way: 57.6% of every warm month in the whole forty-five year record has happened in the last ten years.
Why It Matters Here Specifically
Warm sea is what bleaches coral, and it is what typhoons run on. The Philippines has a great deal of both.
I have deliberately not joined this to reef maps or storm tracks — the reef data carries a licence this site does not use, and attributing any single storm to any single degree is not something a temperature grid can do. So this page says what the water did, and stops.
The Warmest Month
2020-07, at 30.4°C averaged across every square of sea in the box — +1.28°C above what that month used to be.
Of the 15 warmest months ever recorded there, 12 have happened since 2010.
How I Got It Without Downloading Anything
The file holding all this covers the entire planet. I needed about a sixth of one per cent of it.
It turns out you can say so in the web address: which months, which latitudes, which longitudes. The server cuts the slice and sends back plain text. 5 requests, a few megabytes each, instead of a download that would have taken all day and filled a disk.
One Thing I Had To Be Careful About
Land is in the grid. An island square does not come back empty — it comes back holding minus ten to the thirty-sixth power, a stand-in number meaning "no sea here".
Average without noticing and your answer is not a temperature at all. So every square is checked across the whole record, and only the ones that are sea in every single month are counted. That is the 416 squares thrown out, and it is why the map has the Philippines cut out of it in the shape of the Philippines.
Want to see all the charts and data tables?
View the Full Analysis →