Moreover, while the north-westerly wind that carries their smoke to Delhi slackened in the festival’s aftermath, easing the impact on the Capital, it is forecast to return on Wednesday and Thursday, an HT analysis of satellite and weather data shows. Farm fires in Punjab and Haryana hit their highest count of the season on Diwali even as new estimates put the scale of the problem vastly higher than what’s being counted.
Using winds from two weather models, the US Global Forecast System (GFS) and the European Centre for Medium-Range Weather Forecasts (ECMWF), HT traced where the air reaching Delhi at 2pm each day had been over the previous three days. On Diwali, that air had come through the fire belt, the farmland of Punjab and northern Haryana where most of the fires burn. NASA’s fire count, the one most often quoted, shows a far smaller rise.
Till October 28, INSAT-3DS, a weather satellite run by the Indian Space Research Organisation ( ISRO ), detected almost no farm fire in the two states. From Oct 29 the count rose every day, from 18 to 447 on November 8, Diwali , and the daily average in the week to November 9 was 12.5 times that of the week to November 1. The count fell sharply on November 9; the reason is not known. (See Chart 1) A different pattern emerges if the method of detection is changed. The model expects about 14,000 fires, as MODIS would count them. On November 9 and November 10 it came from the east and north-east, passing no INSAT-3DS detections and no more than nine NASA-detected fires. It too hit its season high on Diwali, at 385, but its daily average in the week to November 9 was only 2.4 times that of the week to November 1.
Because nASA counts individual fires and INSAT-3DS counts larger hot patches of ground. (See Chart 1), hT compared only how fast the two counts grew,.
Hiren Jethva, an atmospheric scientist at NASA’s Goddard Space Flight Center, wrote on X on October 3 that a statistical model, which predicts the number of fires from how green the crop was as measured by NASA’s MODIS satellite instrument, “ranks 2026 Punjab – Haryana post-monsoon fire season as one of the intense burning periods”. A CAQM official, when contacted, said the fact that fields are being set on fire later in the day is well-known now. “The Indian Agricultural Research Institute (IARI) has also begun utilising the AQUA satellite to capture instances later in the day, but counts beyond 4 pm are still being missed,” he said, adding they are putting to use drones and even low-cost sensors to gather more data on-ground.
NASA’s satellites have missed more of the stubble burning season after season as the activity moved to later in the day, so a comparison with past counts would mostly measure how much they missed. ISRO’s counts are not comparable from one season to the next. The closest like-for-like measure is the area burned, which the research group iFOREST maps from European Sentinel-2 satellite images; burnt fields show up in them whatever time of day they were set alight.
HT cannot check that ranking against the fire counts of earlier years.
They cross Punjab in daylight once, in the early afternoon; this season, 98% of the fires INSAT-3DS detected came between 4pm and 6pm. Most of the burning now happens after NASA’s satellites have passed.
Jethva wrote that actual fire counts for 2022 to 2025 were “multifold lower” than the model expected because peak burning moved to the late afternoon, which NASA’s fire-counting instruments, MODIS and VIIRS, do not see. (See Chart 3)
