Pune has experienced its chilliest start to December in the last ten years, with weather data revealing a significant and sustained drop in nighttime temperatures. Information from the India Meteorological Department (IMD) and daily records indicates that the first fifteen days of the month were notably colder than any corresponding period since 2014.
A Decade-Low in Minimum Temperatures
The most striking evidence of the cold spell is the average minimum temperature recorded from December 1 to 15, which stood at 10.66°C. This figure is markedly lower than the averages for the same timeframe over the past ten years. The cold was not just a brief dip but a persistent trend, with the city witnessing an unusual cluster of intensely cold nights.
Specifically, from December 9 to 15, Pune's mercury plunged into single digits on at least seven consecutive nights. The temperatures during this period were:
- 8.9°C on December 9
- 8.4°C on December 10
- 7.9°C on December 11
- 8.3°C on December 12
- 8.8°C on December 13
- 9.4°C on December 14
- 9.0°C on December 15
This concentration of sub-10°C nights in early December is unprecedented for the city in the last decade. For comparison, previous years saw far fewer such cold nights: five in 2016, two in 2022, and just one each in 2018 and 2024 within the same December 1-15 window.
Meteorological Reasons Behind the Chill
IMD officials have pinpointed a clear combination of factors responsible for the unusual cold. They attribute the sharp drop to persistent northerly and northwesterly winds, combined with clear night skies and very low humidity levels. This trio of conditions significantly enhanced radiational cooling, allowing heat to escape rapidly after sunset and causing temperatures to fall sharply.
An unnamed IMD expert provided a deeper synoptic explanation. He detailed that a strong anti-cyclonic circulation at the mid-tropospheric level, centred over Gujarat, persisted for several days. This system channeled cold, dry winds from the north across central India, encompassing Madhya Pradesh and Maharashtra, and directly impacting Pune.
"The system led to very low moisture and humidity levels and largely clear skies, which enhanced radiational cooling during night hours," the official explained. He added that with minimal moisture in the air, heat loss after sunset was rapid, leading to the sharp overnight drops. Interestingly, daytime temperatures remained relatively high, around 29–30°C, creating a stark contrast between day and night.
Looking Ahead and Global Context
The official noted a slight warming trend after the temperature hit the lowest point of 7.9°C on December 11. This change occurred as the dominant anti-cyclonic circulation began to shift, allowing easterly winds from tropical regions to slowly influence the area's weather pattern.
While global weather discussions have mentioned events like sudden stratospheric warming and disturbances in the polar vortex, which can push cold air into lower latitudes, the IMD official clarified that a direct link to Pune's current conditions remains unverified. "The influence of La Niña conditions, persistent anti-cyclonic circulation and low humidity levels were clearly evident, but any impact from polar vortex-related processes could not be stated with certainty," he concluded.
This extended cold spell, documented by IMD data and highlighted by weather bloggers like Vagaries of Weather, underscores a significant deviation from Pune's typical early winter weather pattern, marking it as the coldest start to December the city has seen in ten years.
