BOM Relative Niño 3.4 (Weekly)

NOAA isn't the only weather service correcting El Niño readings for a warming ocean. Australia's Bureau of Meteorology (BOM) publishes its own weekly relative Niño 3.4 index — the same idea as RONI, computed independently, on its own schedule and its own threshold.

The logic mirrors RONI's: a raw Niño 3.4 reading means less than it used to, because the whole tropical Pacific has warmed over decades, so BOM nets out that shared background before publishing a number. Where the two diverge is cadence and calibration. RONI is a three-month seasonal average, updated once a month alongside NOAA's official outlook; BOM's relative Niño 3.4 updates every week, closer to the pace of the conventional weekly Niño 3.4 reading most headlines quote. And BOM sets its own El Niño threshold for this index at +0.8°C — not NOAA's ±0.5°C, used for both the conventional reading and RONI. The two thresholds aren't interchangeable and shouldn't be compared as if they were the same scale.

The current reading is +1.94 for the week ending 26 July 2026 — comfortably above BOM's own +0.8°C bar, and still below the conventional weekly Niño 3.4 anomaly for the same week, the same relative-versus-raw gap that motivates RONI in the first place. Track all three numbers side by side on the dashboard, where each carries its own agency and threshold rather than one shared number standing in for all of them.