Seasonal Rainfall Outlook Platform
Jan 2027 outlook · ONDJ 2026/27 — September initialization · ONDJ R3 (Deyr) rainfall domain

September initialization · ECMWF SEAS5 calibrated with CHIRPS · ONDJ R3 (Deyr) rainfall domain

Jan 2027 rainfall outlook

Research reconstruction · not an official EMI or ICPAC forecastTarget period starts 1 Jan 2027

The forecast is close to climatology in the ONDJ R3 (Deyr) rainfall domain: no tercile stands out on average. Mean forecast rainfall is 12 mm against a 1993/94–2024/25 average of 10 mm (+2 mm, +24%).

Average local probability

Below normal 32%Near normal 33%Above normal 36%

Each grid cell has its own tercile probabilities; these are their averages over the 62% of the area that has probabilities. They are not the probability that the area-total rainfall falls in a category.

Map of Jan 2027 tercile probabilities for ONDJ R3 (Deyr) rainfall domain
Tercile probabilities, Jan 2027, ONDJ R3 (Deyr) rainfall domain. Open the map viewer below for other products. Smoothed for display; switch to Grid cells to see the values as computed.

Rainfall amount

Forecast mean12 mm
1993/94–2024/25 average10 mm
Anomaly+2 mm (+24%)

Amounts cover 100% of the area. They come from the amount-corrected ensemble, calibrated separately from the probabilities, so the two can differ slightly.

Forecast signal

No clear tilt (close to climatology)

Largest area-average probability 36%, compared with a one-third reference. The local climatological probabilities (observed tercile frequencies in the training years) are close to, but not exactly, one-third. Based on probabilities only.

Historical skill — ONDJ R3 (Deyr) rainfall domain

Small estimated improvement; skill uncertain

Probability skill (RPSS) +0.002 for Jan, cross-validated 1993–2016 (95% interval −0.013 to +0.016); better than climatology in 13 of 24 years. One-target p = 0.400; adjusted for testing 5 targets (Holm), p = 0.799 (not significant after adjustment). Details

Signal strength describes how far this forecast's probabilities depart from climatology. Historical skill describes how forecasts made the same way scored in past years. A strong signal is not a confidence rating.

All targets in this cycle

← Dec 2026

The targets as a table
ONDJ 2026/27 targets, ONDJ R3 (Deyr) rainfall domain. Probabilities are average local probabilities.
TargetPeriodBelow / near / aboveProbability coverageAnomalyVerification status
ONDJ 2026/271 Oct 2026 – 31 Jan 202716% / 26% / 58%100% of area+77 mmTarget period ongoing (ends 31 Jan 2027)
Oct 20261 Oct 2026 – 31 Oct 202626% / 31% / 42%100% of area+24 mmTarget period ongoing (ends 31 Oct 2026)
Nov 20261 Nov 2026 – 30 Nov 202620% / 25% / 54%100% of area+40 mmTarget period starts 1 Nov 2026
Dec 20261 Dec 2026 – 31 Dec 202636% / 26% / 38%100% of area+5 mmTarget period starts 1 Dec 2026
Jan 20271 Jan 2027 – 31 Jan 202732% / 33% / 36%62% of area+2 mmTarget period starts 1 Jan 2027

Probability coverage is the share of the area with tercile probabilities; averages are over that share only. Cells with very little reference-period rainfall have no terciles.

Maps

How to read this map

Grey, white and blank areas; smoothing and resolution

Light grey: outside the selected area. Dark grey: inside the area but without values, for example cells where reference-period rainfall is too small for tercile categories, or (percent maps) below 10 mm. White on tercile maps: no category reaches 40%, or two categories tie. Sea cells have no CHIRPS data.

Smoothing and resolution. Maps are drawn on a 12× finer display grid with light Gaussian smoothing (σ = 0.6 grid cells); all numbers on this page use the original 0.25° grid. The model's own resolution is about 1°: each model cell covers 4×4 grid cells, so detail within a 1° box comes from local CHIRPS rainfall statistics used in the amount correction, not from the model.