Bihar is experiencing one of its worst unseasonal rainfall episodes of 2025 due to Cyclone Montha, which has battered the state with heavy downpours since late October. However, significant relief is on the horizon. According to the India Meteorological Department (IMD) and leading weather forecasting agencies, the destructive rainfall is expected to completely end by November 3-4, 2025, with substantial weather improvement beginning as early as November 2.
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The well-marked low-pressure system—the remnant of Cyclone Montha—is weakening as it moves northeastward toward the Himalayan foothills. This system, which caused devastating crop damage and waterlogging across Bihar’s agricultural regions, will lose its potency once it encounters the rough and hilly terrain of Sikkim and Sub-Himalayan West Bengal. The IMD’s latest press release issued on November 1, 2025, confirms that the cyclonic circulation is becoming less marked and will dissipate significantly over the next 24-48 hours.
Timeline for Rainfall Cessation
Heavy rainfall is currently concentrated over northeast Bihar districts including Kishanganj, Katihar, Araria, Purnea, Supaul, and Madhepura, which may continue experiencing light to moderate showers through Saturday, November 1, and into early Sunday, November 2. However, meteorologists predict that substantial improvement will become visible from November 2 afternoon onward.
By Monday, November 3, 2025, skies across Bihar will clear completely, marking the official end of this unseasonal rainfall episode. The state will transition into predominantly sunny and dry conditions, which is the normal weather pattern for November across Bihar. From November 4 onward, Bihar will experience typical post-monsoon weather characteristics—clear skies, moderate temperatures, and virtually no precipitation expected through mid-November.
Meteorological Details of System Weakening
The low-pressure system that developed over northwest Jharkhand and adjoining Bihar has already begun its northeastward movement. As of November 1, 2025, at 8:30 AM IST, the system was positioned over northern parts of Gangetic West Bengal and is forecast to move further north-northeastward, becoming progressively less marked during the next 12 hours.
The associated cyclonic circulation that extended up to 5.8 kilometers above mean sea level is breaking apart due to the disrupting effects of mountainous terrain. Once the system crosses into the foothills of Sikkim and Sub-Himalayan West Bengal, the friction and orographic effects will scatter and weaken the circulation beyond any capacity to generate further heavy rainfall over Bihar.
November Weather Expectations
Following the clearance of Cyclone Montha’s effects, Bihar will settle into its characteristic November weather pattern. The entire month of November experiences virtually no rainfall, with historical data indicating fewer than 2 rainy days throughout the 30-day period. Average November rainfall is less than 10 millimeters across the state, and November 2025 is expected to follow this pattern closely.
Daytime temperatures are forecast to stabilize around 29-31°C (84-88°F), while nighttime temperatures will gradually decrease to around 18-21°C (64-70°F) as the month progresses. Wind speeds will moderate to gentle breezes averaging 9 kilometers per hour. Humidity levels will decrease significantly as drier conditions establish themselves across the state.
Potential Minor System on November 5-7
Weather forecasters have flagged a possibility of a very weak weather system developing over the Bay of Bengal between November 5-7, 2025, which could bring isolated, light, and sporadic showers to limited areas of Bihar. However, this system is expected to remain substantially weaker than Cyclone Montha and will not produce the widespread heavy rainfall experienced during the current episode.
For farmers who suffered substantial crop damage during Cyclone Montha’s assault, the end of rainfall by November 3-4 provides an opportunity to assess damage, harvest salvageable crops, and prepare fields for the Rabi (winter) crop season. The return to dry November weather will facilitate field drainage and allow agricultural activities to resume normally.
