25th October

East Coast Braces up for Potential Cyclone. 

Track..

After Landfall North due to 200 level wind shear

Meanwhile, NEM ACTIVE as the System from Arabian Sea crosses through the Land.. 

Mumbai Outlook and Synoptic Situation of Arabian and Bay Systems.

23rd Night Post:.. Arabian and Bay Systems outlook below. 

Mumbai region may see a slight drop of 1-2°C to (34/36°) in the day and to (22/23°) at night temperatures 27th onwards from the current values. 

As the Arabian Sea low dissipates and the Bay low intensifies by Sunday, weather over Maharashtra will remain dry. 

Slight drop in temperatures likely for Madhya Maharashtra region next week, with nights and early mornings turning pleasant (below 17°C in areas of Pune/Nashik/Satara). 

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Synoptic Situation 

First Cyclone Watch for 2026 over the North Indian Ocean!

The Madden-Julian Oscillation (MJO) has been active since last few days over the Indian Ocean (Phases 2-3). Two lows had formed earlier, one in the Arabian Sea (moved towards Somalia), one in the Bay of Bengal off Tamil Nadu coast and a weak tropical cyclone (named Agueda) in the southern Indian Ocean. 

The earlier two lows have now dissipated, but two new low pressure areas have formed, one over the southeastern Arabian Sea off Keralam coast and the other over central Bay of Bengal. 

Although as of present, the clouds appear little more dense over the Arabian Sea and the sea surface temperatures are favourable for intensification, higher vertical wind shear is likely preventing this low from developing further. This low could eventually move east and dissipate while crossing Keralam coast by 25th October, bringing moderate-heavy rains for southern peninsula, mainly Keralam, and Western Ghats. 

On the other hand, the atmospheric and oceanic conditions are favourable for the further development and intensification of the Bay of Bengal low pressure area into a depression, deep depression and thereafter into a tropical cyclone over next 48 hours. 

This will be the first cyclone over north Indian Ocean for 2026 and as per the nomenclature, it will be called "Arnab". 

Guidance from various weather models suggest the Bay low to intensify into a strong cyclone and move towards central-north coastal Andhra Pradesh by 27th/28th October. The east coast from central AP upto south Odisha could experience impacts from this developing system, with gusty winds and heavy rains. Storm surge is possible for north coastal AP and south Odisha coasts.  

There could be some change in the expected track of this cyclone, will be updated in subsequent posts.

850 hPa winds are shown below. Combined effect of both the lows would result in gusty southwesterly winds for south Keralam and Sri Lanka for the next 2 days.

More updates in the coming days...

Meteorological Status of El Niño ( Below)

 Vagaries was not absolutely off the mark in the forecast for 17th to 19th for South Maharashtra... Pune, *Rainfall(mm) Pune from 0830 hrs IST of 19th October 2026 to 0830 hrs IST of 20th October 2026*

HADAPSAR 14.0, MAGARPATTA 14.0, CHINCHWAD 3.0, NARAYANGOAN 1.5, HAVELI 1.0, NDA 0.5

& Mahabaleshwar did get moderate rainfall on 18th /19th.

2 dayscAccumulated rainfall map

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• Meteorological Status of El Nino
• 
  
• The latest weekly relative Niño3.4 index value for the week ending 11 October 2026 is +2.81 °C, well above the El Niño threshold (+0.80 °C). 
• In the bureau weekly sea surface temperature (SST) data, (GAMSSA, starting in 2008) this is the highest value on record, exceeding +2.78 °C for the week ending 22 November 2015
• Outlook & Forecast
  • Peak Intensity: Models indicate the event will peak around November–December 2026, with a high probability of becoming a historic, ultra-strong event exceeding pre-1950 levels.
  • Duration: El Niño conditions have a 100% probability of persisting through the remainder of 2026 and boreal spring (MAM) 2027.
  • Transition: A gradual weakening is expected by mid-2027, with ENSO-neutral conditions favored by summer (JJA 2027).

  

  
  

  

  
  

  

  
  

  

  
  

  
  

NEM VERY ACTIVE IN T. N.

 18th October Post

NEM VERY ACTIVE IN T. N. 

TEN HOTTEST IN INDIA TODAY 

17th October 

IMD-based 1–15 October average maximum for Mumbai and Pune

IMD-based 1–15 October average maximum 

For Mumbai Santacruz 

For Pune

Year    Average maximum

1991.   32.81°C

1992.  30.41°C

1993.   31.12°C

1994.   32.34°C

1995.     31.29°C

1996.     29.86°C

1997*.    32.79°C

1998.   30.39°C

1999.   29.87°C

2000.   32.1°C 

2001.   30.21°C

2002.   34.78°C

2003.   32.97°C

2004.   30.88°C

2005.    30.87°C

2006.    31.04°C

2007.    32.50°C

2008.    31.86°C

2009.    30.51°C

2010.    32.09°C

2011.    31.94°C

2012.     31.43°C

2013.     30.43°C

2014.     33.34°C.    

2015.     32.35°C

2016.     28.78°C.  

2017.     30.68°C

2018.     32.41°C

2019.    30.22°C

2020.    30.26°C

2021.    31.23°C

2022.    28.93°C

2023     33.09°C

2024.    32.58°C

2025.    31.40°C

2026.    34.97°C

14th October Post

1. Low Pressure forming in shear zone Trough in T. N. Can bring in the NEM into Tamil Nadu on the 17th.... *See NEM note below*

2. Low pressure moves NW through T. N. into Karnataka towards South Maharashtra. 

3. Heavy thundershowers in Bengaluru from 16th - 23rd.

4. Unseasonal rains expected in South Maharashtra and along Ghats on 18th - 21st.. Mahabaleshwar : Thundershower expected on 17th/18th.

5. Pune :Thundershowers expected in Pune on 19th/20/21..Heavy on 21st... Wet Dussehra.

6.  Mumbai Rain expected in Mumbai from 18th - 20th...Wet Dussehra.

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*NEM Arrival Criteria :

On many occasions, there is no clear indication between the withdrawing SWM and setting NEM. Often one tends to merge into another.

So, setting a date for the commencement of NEM is difficult, and sometimes not possible.

-The main has its origin, its "Power House", is at the Mascrene Highs off Madagascar. The NEM has its origin round a large anti-cyclone over Siberia.

-Jet streams at 200 hpa are common to both the monsoons.

In the SWM, the Tropical Easterly Jet stream dominates the Peninsula, while the Sub-tropical Westerly Jet Stream is the feature of the NEM.