Brazil and Argentina together out-ship the United States in beans, and their crop is made in a window the northern market once slept through: Mato Grosso plants on the September–October rains, southern Brazil and the Pampas fill pods in the January heat. When this desk's rainfall ledger goes dry, Chicago reprices world protein.
ENSO state · through Sep 2026
very strong El Niño+3.40 · strengthening · Oct 2026 provisional +3.83
The Forecast Network's ERA5 multivariate ENSO index (the series behind celsius.earth/enso); positive is El Niño-like. Monthly means arrive about six weeks after the month; the provisional month is ERA5T and may still move.
Current stage
Planting-rains onset · Planting★
Temp, next 2 wk
-0.5°C vs normal
Rain, next 2 wk
115 % of normal
SEAS5, next 3 mo
+0.9°C vs hindcast
Obs rain, 3 mo
93 % of normal
ENSO
very strong El Niño +3.4
The daily sheet · 2026-10-21 to 2026-11-03
Temperature anomaly · °C vs 1991–2025 normal
Rainfall · mm per day, brass dash = normal
Day-by-day ensemble means from the same ECMWF extended run as the weekly ledger — the short-term sheet a desk reads each morning. Days are UTC.
The six-week ledger · ECMWF extended ensemble, 2026-10-21 00z
Temperature anomaly · °C vs 1991–2025 normal
Rainfall · mm per week, brass dash = normal
The belts, first fortnight
Region
Temp anomaly
Rain
% of normal
Brazil Mato Grosso / Cerrado
+5.5°C
66 mm
87%
Southern Brazil (RS/PR/SC)
-3.0°C
128 mm
148%
Argentina Pampas
-5.0°C
49 mm
103%
Ensemble-mean weekly aggregates over the desk's growing belts (land cells, production-weighted); whiskers show the ensemble spread carried with the mean — an upper bound for a weekly average. Weeks run from the initialisation date.
The plates · the fortnight on the map
Temperature anomaly · Week 1 · 2026-10-21 → 2026-10-27
Rainfall, percent of normal · Week 1 · 2026-10-21 → 2026-10-27
Temperature anomaly · Week 2 · 2026-10-28 → 2026-11-03
Rainfall, percent of normal · Week 2 · 2026-10-28 → 2026-11-03
Temperature anomaly (°C vs normal)≤ −4−4 to −2−2 to −1−1 to −½near normal+½ to +1+1 to +2+2 to +4> +4
Rainfall, percent of normal (% of normal rain)< 4040–6060–80near normal120–150150–200200–300> 300
EC-46 ensemble-mean weekly fields at 0.25°, painted in the Herbarium stepped ramps over the desk's belts (the oxblood rectangles). Near-normal stays paper; sea and no-data carry no ink; rainfall percent is unpainted where the weekly normal is under 2 mm. Cells are honest — drawn at the data's own resolution.
The seasonal ledger · SEAS5, initialised Oct 2026
Run-to-run · the last 6 initialisations
A forecast that holds its shape across initialisations deserves more weight than one that just appeared.
Latest run, month by month
Month
Temp anom
Rain anom
% of normal
Topsoil moisture anom m³/m³
Oct 2026 ◔
+0.1°C
+27 mm
118%
+0.011
Nov 2026
+0.9°C
+19 mm
111%
+0.001
Dec 2026
+0.9°C
+29 mm
115%
+0.009
Jan 2027
+0.9°C
+27 mm
113%
+0.011
Feb 2027
+1.0°C
+21 mm
111%
+0.010
Mar 2027
+1.1°C
+23 mm
113%
+0.011
Apr 2027
+1.1°C
+23 mm
118%
+0.007
◔ part elapsed. Anomalies vs the store's ERA5 hindcast climatology; percent-of-normal vs the AgroClim 1991–2025 normals. Topsoil moisture is volumetric water in the top 7 cm — negative is drier than the hindcast normal.
Rain that actually fell · CHIRPS, through Dec 2025
Monthly rainfall over the belts · mm, brass dash = 1991–2020 normal
Last 3 months 93% of normal
CHIRPS v3.0 satellite-gauge rainfall sampled at a lattice of land points across the desk's belts, production-weighted. Observed data, not a forecast.
The crop calendar · what this weather means now
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Planting-rains onset ★
Planting
Pod fill — heat & rain watch ★
Harvest & safrinha handoff
★ market-critical stage · the outlined column is the current month.
What the desk watches
The onset of the Mato Grosso wet season: a late start pushes planting, which pushes the safrinha corn window behind it — one delay, two crops.
January–February rain and heat over southern Brazil and Argentina, where a flash drought at pod fill is the classic bull market.
Harvest-season rain in March, when mud and sprouting meet the export lineup.
Climate drivers
La Niña is the standing threat: it dries southern Brazil and Argentina in exactly the pod-fill months (2021–22 cut Argentina by a third). El Niño flips the risk northward as excess rain on the Mato Grosso harvest.
