How big does this one get?
A peak above +2.0 °C is settled. What is still open is how far past it: 70% for a peak beyond +3.5 °C, a level no event in the instrumental record has reached. Subsurface heat is at +2.96 °C, the highest in the 47-year record.
01 · Observed
Subsurface heat is at the highest value in the 47-year record. Above 1997's own October peak of +2.56, with roughly three months of seasonal build still ahead.
Niño 3.4 is at +2.6 °C this week, and 11 westerly wind bursts have been recorded since 1 March.
Cumulative westerly wind anomaly since 1 March, against the same construction in the analog years. 2025 is the non-event reference, and the contrast is what makes the rest legible.
02 · Outlook
Three rungs. A rung retires when it reaches the display bound rather than when someone edits this page.
And where those numbers have come from since April, which one week cannot show. A line begins at the issue its rung was first published.
03 · Trajectory
Every event year against this one, with the forecast fan carried forward. The bands are the spread, not a second opinion.
04 · Provenance
What each source said, when it said it, and every caveat that governs a figure above. One register rather than three.