Weather Bee: October is still cool, but warmer than earlier this month

Maximum temperatures were still cooler than normal in large parts of northern India, although they might have warmed up compared to the first nine days.

Up to last week, India’s average maximum temperature – a proxy for daytime temperatures – in October was so far below usual that the month on average was running fifth coolest since 1951, as HT reported at the time. That downward deviation’s impact was present this week too, but large parts of northern India are likely to have felt the cool weather easing somewhat, an HT analysis of the gridded data of India Meteorological Department (IMD) suggests. This has happened because the weather systems that were keeping the weather cool have subsided.

People cross a footover bridge amid low visibility in Gurugram on Friday. (PTI)

The impact of the downward deviation in the month’s first nine days can be seen in the fact that October so far is still ranked sixth coolest since 1951 by maximum temperature. However, as this revised rank suggests, maximum temperatures have warmed up this week. This can be seen by comparing this daily temperature this year and the average in the 1981-2010 period, which IMD considers as the normal for temperature. India’s average maximum kept going further below normal up to October 6 before it started climbing back up. To be sure, this was not a quick correction. October 16 was the first day this month that turned marginally warmer than normal.

India's average maximum temperature

How did this change take place? This can be seen by tracking maximum temperature trends geographically. As the accompanying map shows, the northern and western parts of the country were majorly responsible for the country-level trends in the first week of October, although even central and eastern states experienced cooler than normal maximums. The downward deviation in these places significantly eased in the week ending October 16, bringing the national average closer to normal. The increase in maximum temperatures was big enough to make the week ending October 16 warmer than the October 1-9 period in large parts of the country, which is not expected when moving closer to winter.

Maximum temperature's deviation in 2025 from 1981-2010 average

Maximum temperature's deviation in 2025 from 1981-2010 average

Change in average maximum temperature

Part of geographical trends in maximum temperature can be explained by the trends in rainfall. Almost the entire northern half of India did not get a single drop of rain in the week ending October 17 (rainfall data is published for the 24 hours ending 08:30 AM on the date). This is a decline of at least one day compared to the first ten days of the month across most of the country and at least three days across most of northern India. This likely increased daytime temperatures this week, because cloudy weather prevents sunlight from reaching the surface.

Change in number of days of rain

Number of days it rained in the week ending October 17

To be sure, maximum temperatures were still cooler than normal in large parts of northern India, although they might have warmed up compared to the first nine days. This is likely because of winds from the hills, which were responsible for adding to the chill in early October. The snowfall in early October in India’s hilly states in the north led to a rapid accumulation of snow pack. With snowfall subsiding, this snow pack has decreased somewhat but not by much. This could be one reason why northern India is still somewhat cool.

Snow water equivalent over India's northern states