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Rain Futures Index Desk

NCDEX rainfall futures · Cumulative Deviation Rainfall
RAINCHNNAI As on Friday, October 16, 2026 09:30 AM · RAINMUMBAI As on Wednesday, September 30, 2026 09:30 AM · page generated 16 Oct 2026 11:18 IST
What these indices are. Each one settles on how far a city's rainfall runs above or below normal. The index opens on day one of the season at the whole season's normal — 2,206.7 mm for Mumbai, 998.25 mm for Chennai — then each day adds the actual rainfall at that city's two IMD observatories and subtracts the normal for that date. Rising means wetter than normal; falling means drier. One millimetre is worth Rs 50 per lot on both, so either panel can be read in rupees as well as rainfall.
Between them the two contracts cover June to December: Mumbai runs the southwest monsoon from 1 June to 30 September, Chennai the northeast monsoon from 1 September to 31 December. They overlap only in September. The two are shown on separate axes on purpose — their starting points differ by more than a factor of two, and so does how far each typically travels in a season, so a shared scale would flatten one and mislead on both.

RAINCHNNAI · Chennai · northeast monsoon live day 46 of 122

Official spot
860mm
16 Oct · Rs 42,986/lot
vs anchor
-139mm
deficit
Model spread
115mm
at 30 Oct · Rs 5,738/lot
Season rank
0th pct
of 5 seasons on this date
600 800 1000 1200 1400 1600 1800 Sep Oct Nov Dec anchor 998.25 VM-AIFS 902 VM-IFS 787
2026 official spotVM-AIFS projectionVM-IFS projection5-season median10th–90th percentile
Observed line is the CDR spot NCDEX publishes; the band is the same index over its published back-computed seasons. Dashed forecasts start from the latest published spot. They carry no bias correction: out of fold, every correction scored worse than leaving the model alone (VM-AIFS 122 days, leave-one-month-out; VM-IFS 242 days, leave-one-season-out).
DateLeadVM-AIFS mm VM-IFS mmLPAVM-AIFS CDR VM-IFS CDRGap
17 Oct111.417.48.3863869-6
18 Oct219.822.416.0867875-9
19 Oct39.72.89.5867868-2
20 Oct410.618.411.0866876-10
21 Oct527.917.410.7884883+1
22 Oct627.313.08.9902887+15
23 Oct719.68.79.4912886+26
24 Oct812.59.815.6909880+29
25 Oct912.76.115.8906871+36
26 Oct1013.71.913.6906859+47
27 Oct1124.11.121.4909839+70
28 Oct1222.20.518.7912820+92
29 Oct1313.30.518.5907802+105
30 Oct1410.30.516.1902787+115
Where the two sources diverge, that gap is the honest uncertainty — and it is wider than either model's own error statistics imply. Both under-forecast heavy rain badly, so treat any active spell in these trajectories as a lower bound.
ContractLast vs spotAs of
2026-09-29(Sep Fut)941.00+81.3*30 Sep
2026-10-30(Oct Fut)869.00+9.3*15 Oct
2026-11-27(Nov Fut)873.00+13.3*15 Oct
2026-12-30(Dec Fut)878.00+18.3*15 Oct
* these are the last daily futures prints and they predate the current spot, so that column compares two different days. The exchange's series feed carries one value per calendar day and publishes the current day's only once it settles. The front-month row above is the live last-traded price and is the one to read intraday.

RAINMUMBAI · Mumbai · southwest monsoon off-season season 01 Jun–30 Sep

Official spot
2,243mm
30 Sep · Rs 112,153/lot
vs anchor
+36mm
excess
Model spread
6mm
at 30 Sep · Rs 323/lot
Season rank
0th pct
of 5 seasons on this date
1600 1800 2000 2200 2400 2600 2800 3000 3200 Jun Jul Aug Sep anchor 2206.7 VM-IFS 2237 VM-AIFS 2231
2026 official spotVM-AIFS projectionVM-IFS projection5-season median10th–90th percentile
Observed line is the CDR spot NCDEX publishes; the band is the same index over its published back-computed seasons. Dashed forecasts start from the latest published spot. They are bias-corrected (VM-AIFS 200 days, leave-one-season-out; VM-IFS 325 days, leave-one-season-out).
DateLeadVM-AIFS mm VM-IFS mmLPAVM-AIFS CDR VM-IFS CDRGap
29 Sep10.64.98.82,2332,237-4
30 Sep12.64.74.72,2312,237-6
Where the two sources diverge, that gap is the honest uncertainty — and it is wider than either model's own error statistics imply. Both under-forecast heavy rain badly, so treat any active spell in these trajectories as a lower bound.
ContractLast vs spotAs of
2026-06-29(Jun Fut)2,096.00-147.1*30 Jun
2026-07-30(Jul Fut)2,635.00+391.9*31 Jul
2026-08-28(Aug Fut)2,389.00+145.9*31 Aug
2026-09-29(Sep Fut)2,244.00+0.930 Sep
* these are the last daily futures prints and they predate the current spot, so that column compares two different days. The exchange's series feed carries one value per calendar day and publishes the current day's only once it settles. The front-month row above is the live last-traded price and is the one to read intraday.

Verification — out of sample, RAINCHNNAI, RAINMUMBAI

How each model has actually performed once the real rainfall was published. Bias is the average miss and its sign shows the direction — positive means too wet. MAE is the typical miss ignoring direction; lower is better on both.

BasisModelLeadn BiasMAERMSE
ChennaiAIFSD+147+1.014.386.72
ChennaiAIFSD+236-0.143.956.06
ChennaiAIFSD+335+0.973.004.62
ChennaiAIFSD+435+0.643.595.43
ChennaiAIFSD+533+1.503.374.89
ChennaiAIFSD+632+0.343.945.80
ChennaiAIFSD+731+2.093.765.46
ChennaiAIFSD+831+2.414.015.69
ChennaiAIFSD+930+2.204.917.10
ChennaiAIFSD+1029+3.534.416.31
ChennaiAIFSD+1128+4.144.836.75
ChennaiAIFSD+1227+5.155.518.14
ChennaiAIFSD+1324+3.444.105.91
ChennaiAIFSD+1423+3.603.946.36
ChennaiIFSD+141+2.505.267.19
ChennaiIFSD+237+1.263.765.80
ChennaiIFSD+337+1.184.116.19
ChennaiIFSD+436+1.603.785.38
ChennaiIFSD+534+0.953.555.53
ChennaiIFSD+633+1.513.885.70
ChennaiIFSD+732+1.774.105.62
ChennaiIFSD+832+2.514.236.07
ChennaiIFSD+931+2.964.677.46
ChennaiIFSD+1030+2.643.975.85
ChennaiIFSD+1129+4.574.697.84
ChennaiIFSD+1227+5.256.3410.21
ChennaiIFSD+1326+4.836.0110.15
ChennaiIFSD+1425+3.383.795.48
MumbaiAIFSD+141-1.325.358.56
MumbaiAIFSD+230+1.315.829.45
MumbaiAIFSD+329-0.534.447.36
MumbaiAIFSD+428+2.666.5810.21
MumbaiAIFSD+527-0.095.036.77
MumbaiAIFSD+623+5.608.2112.80
MumbaiAIFSD+722+1.966.9810.40
MumbaiAIFSD+821+6.9210.5515.88
MumbaiAIFSD+920+0.826.4610.59
MumbaiAIFSD+1019-0.6110.1316.41
MumbaiAIFSD+1118+0.088.4716.74
MumbaiAIFSD+1218+0.509.6112.91
MumbaiAIFSD+1316+3.2414.5322.26
MumbaiAIFSD+1417+3.1413.5520.98
MumbaiIFSD+139+3.498.5710.51
MumbaiIFSD+230+5.678.1810.51
MumbaiIFSD+329+4.836.777.73
MumbaiIFSD+428+4.347.599.95
MumbaiIFSD+527+4.446.948.54
MumbaiIFSD+623+3.988.7012.57
MumbaiIFSD+722+4.7010.3713.92
MumbaiIFSD+821+3.8410.5114.86
MumbaiIFSD+920+3.749.5914.23
MumbaiIFSD+1019+4.4811.5415.75
MumbaiIFSD+1118+5.0310.9514.76
MumbaiIFSD+1218+10.5517.7628.88
MumbaiIFSD+1317+4.7912.5617.16
MumbaiIFSD+1418+2.719.3714.57
48 settlement day(s) scored against the official spot. Below about 30 days this is provisional, not a track record. Scores belong to the basis they were measured on and do not transfer: the northeast monsoon is a different forecast problem from the southwest, so a Mumbai track record says nothing about Chennai skill.