The 77-year record shows four measures trending together: first arrival 18–19 days earlier; +1.2 storms/decade; +6 storm-days/decade; +4.6 kt peak wind within 500 km. All clear p<0.005. All hold within El Niño, La Niña, and neutral years. The trends are not an ENSO artifact.
Earlier, more frequent, more intense — and not explained by El Niño cycles.
All four measures trend together. All hold within each ENSO phase.
Four measures, all moving in the same direction.
Annual trend by linear regression; change per ten years since 1949.
How to read the first row: the first storm of the year reaches the area around Saladita about 2.5 days earlier each decade — meaning the 2020s first-arrival expectation is roughly 19 days earlier than in the 1950s. Around June 4 today versus late June in 1949.
The trend holds within every climate phase.
If the trend were an ENSO artifact it would disappear within each climate phase. It does not.
Warmer Pacific
Cooler Pacific
Neither warm nor cool
In this corridor, La Niña (12.7 storms/yr) and neutral years (13.2) outpace El Niño (11.4) — opposite of the basin-wide pattern. El Niño may push tracks westward toward Hawaii, reducing Mexican coastal exposure while raising basin totals. Observation from data; mechanism unconfirmed.
Storm winds near Saladita are climbing through the record.
Maximum sustained wind speed (in knots; 1 knot ≈ 1.15 mph) among storms passing within 500 km of Saladita, grouped by decade.
Early records are less reliable. Before 1966 (17 years of the record), storms were tracked without satellites — some storms were missed entirely, and the apparent rise in storm counts partly reflects better detection, not more storms. Take the pre-satellite portion of the trend with extra caution.
Geostationary satellite coverage improved further in the late 1970s, catching more short-lived and weaker systems. Some of the count increase after 1978 may reflect this surveillance improvement rather than real activity change.
The p-values are approximations. The test assumes each year is independent, but storm counts in adjacent years are weakly correlated. The true effective sample size is probably 30–50 years, not 77. The trends survive that correction — but the exact p-values quoted here are optimistic bounds, not precise estimates.
The ENSO classification is a simplification. Each year is classified by its July–September climate state, the peak storm quarter. Other climate indices (different months, different measurement methods) would shift some years between categories and could change the edge-case results.
This is a description of the data, not an explanation. The trends are real in the 77-year record. The underlying causes — warming sea-surface temperatures, changing wind patterns, expansion of the tropical belt — are active research topics with peer-reviewed findings. This analysis does not assert a mechanism; it describes what changed.
Mean first arrival ~June 4 — 18 days earlier than 1949. Boris (June 8, 2026) was three days late by today's calendar; by 1949's expectation, two weeks early.Synthesis · June 2026
Sources
NHC HURDAT2 1949–2025. NOAA CPC ONI index (JAS average; ≥+0.5°C = El Niño, ≤−0.5°C = La Niña). OLS regression; all four p-values clear Bonferroni threshold (p<0.0125). Script: scripts/analyze_hurricane_phenology.py → functions/api/_findings_hurricane_phenology.js.