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India’s rich tradition of meteorological practices draws from a blend of spiritual, astrological scientific knowledge that has evolved over millennia. These indigenous forecasting systems, grounded in ancient wisdom, provide sophisticated methods for predicting climate, calculating rainfall and issuing early warnings. In this article, we explore traditional Indian weather forecasting systems, examining their relevance, accuracy, and the role they continue to play in contemporary society. References to rain and weather are found in numerous ancient texts, including the Rigveda, Shrimad Bhagavat, Parashara Samhita, Panini’s Ashtadhyayi (500 BC), and Meghmala (800 AD). These texts, written in various Indian languages, offer insights into rainfall patterns and seasonal changes. In addition to these classical texts, regional literature also plays a significant role in preserving traditional weather forecasting knowledge. Local folklore and sayings, such as Ghagh Bhaddariin Hindi, Bhadali Vakyo in Gujarati, Sahadeo Bhadali in Marathi, provide valuable information on predicting rainfall and other weather-related phenomena. These sayings, often based on observations passed down through generations, continue to influence agricultural practices and daily life in rural India.
PANCHANG: THE ANCIENT INDIAN ALMANAC
The Panchang, an ancient Indian almanac, has long served as a cornerstone of traditional meteorology. It is a comprehensive guide that includes astronomical data, planetary positions and astrological predictions. Far from being merely a religious text, the Panchang is a scientific tool used for forecasting weather patterns, determining the timing of agricultural activities, and planning festivals and events. Every state or region of India has its regional Panchang or almanac to cater to the needs of that particular area. The accuracy of these predictions often rivals that of modern meteorological models, showcasing the advanced understanding of natural cycles that ancient Indian scholars possessed.
There has been tradition in India since ancient times, before the British regime, known as 12 balutedar system (i.e. 12 different vocations in a village) which refers to self-reliance in rural India by supporting each vocation. The balutedars gave services to the farming community, and the farmers gave grains through barter system as yearly payment. There was one vocation among them, known as Gram Jyotishi or Gram Joshi who used to calculate seasonal rainfall, nakshatra-wise rainfall and make other predictions as economic, political and natural calamity, which was known as Mediniya Jyotish. On Varsh Pratipada (Gudhi Padva or Hindu new year, also known as Chaitra Shudhha Pratipada) all villagers gathered and this Gram Joshi read panchang vachan, giving prediction of rainfall pattern, crop yield, general prediction, calamity and political stability, etc. He used technology or methods given in Varahmihira’s Brihat Samhita or Parashar Krushi Samhita. It was known panchang vachan. This was a self-reliant rural system which was prevalent in the pre-British era in different parts of India.
THE ROLE OF NAKSHATRAS AND PLANETS IN RAINFALL PREDICTION
In ancient Indian meteorology, Asterisms (Nakshatras, lunar mansions) and planets were attributed qualities such as soma (cooling) or agni (heating), which influenced rainfall processes. The Vedic seers taught that these qualities gave rise to all phenomena in the universe, including weather. Initially, the art of rainfall forecasting was practiced by a few experts like Garga, Parashara, Narada, Devala, Vashistha, Bhrugu and Varahmihira. For wider regional observations, more experts emerged, leading to the creation of numerous weather prediction rules. Regional observations led to many new weather prediction rules.
Image Courtesy: Astrologerinassam
PRINCIPLES OF RAINFALL PREDICTION IN PANCHANG
- Asterisms and Rainfall: When the Sun and the Moon are in neutral asterisms, there will be winds; when they are in feminine asterisms, there will be lightning and phosphorescence. If the Sun occupies a feminine asterism while the Moon is in a masculine asterism (or vice versa), there will be rain.
- Planetary Conjunctions: When multiple planets gather in a single rashi (zodiac sign), especially if Mars and the Sun are involved, there can be a significant downpour. If the Moon joins this conjunction, heavy rains are likely, regardless of the regular monsoon season.
- Rashi Transitions: Mars transitioning from one to another within two days often brings a perceptible change in the weather, particularly in the rainy season, leading to good rainfall.
- Major Planetary Changes: When major planets (Jupiter, Saturn, Rahu, Ketu) change rashi, especially into a fiery, earthy, watery, or airy sign, significant weather changes occur.
- Retrograde Motion: When planets retrograde or resume direct motion, changes in temperature, humidity and other meteorological disturbances often lead to rainfall. Cyclones, particularly along the Andhra Pradesh coast, are more likely to occur near periods of sunspot maxima when planets such as Jupiter, Saturn, Rahu (Ketu) and Uranus form square (kendra) aspects or conjunctions. The likelihood of cyclones is further increased if Virgo or the 12th house from it are afflicted during this period.
These principles reflect a sophisticated understanding of the interplay between celestial bodies and terrestrial weather patterns, which has been honed over centuries. While some of these methods may seem antiquated in the face of modern meteorology, they offer a fascinating glimpse into the depth of ancient Indian knowledge and its enduring influence on agricultural practices and weather forecasting in the region.
PLANETARY ASPECTS FOR RAINFALL AND FLOODS
- When the Sun overtakes Mars, heavy rainfall can cause river floods.
- If the Moon is in the 7th house from Venus and within view of benefic planets like Jupiter, Neptune, Mercury, or in the 5th, 7th, or 9th house from Saturn, immediate rain is likely.
- Venus in the constellations of Swati, Vishakha and Anuradha often leads to unprecedented rainfall and heavy floods.
- Jupiter in Pisces and Venus in Cancer together are a strong indication of heavy rainfall.
EFFECT OF PLANETARY COMBINATIONS ON EXTREME RAINFALL
Here, we will take the example of Gujarat to understand the effect of planetary combinations on extreme rainfall.
Heavy rainfall and rainy days were categorized on the basis of different threshold values such as 25 mm/d as lower limit to extreme rain of 100 mm/d. Extreme rainfall was analysed using criteria of more than equal or equal to 100 mm per day. The extreme rainfall dates were analysed for finding out predominant planetary combinations for each station by the same method. The predominant planetary combinations found for extreme rainfall (daily rainfall equal to or more than 100 mm) for each station from data of 1980-2014 is analysed as follows.
In South Gujarat (heavy rainfall) zone, or Zone-1, the topmost combination was Moon-Saturn Kranti yuti (MoSaKy) for Navsari and Moon-Saturn Kranti Pratiyuti (MoSaKp) for Valsad. In South Gujarat zone or Zone-2 at Bharuch, there were 15 combinations and Moon-Uranus Kranti yuti (MoUrKy) was topmost. In Middle Gujarat zone or Zone-3, the predominant planetary combination for extreme rainfall was 17 for Anand and 18 combinations for Godhra. The topmost combination was Moon-Pluto Kranti Pratiyuti (MoPlKp) for Anand and Moon-Mercury Kranti yuti (MoMeKy) for Godhra. In North Gujarat zone or Zone-4, the predominant planetary combination for extreme rainfall was 15 for SK Nagar and 10 combinations for Idar. The topmost combination was Moon-Pluto Kranti yuti (MoPlKy) for SK Nagar and Idar. In North-west Gujarat zone or Zone-5 at Bhuj, there were 12 predominant combinations and Moon-Mercury Opposition (MoMeO) was topmost in frequency while for Nalia, there were 16 combinations and Moon Pluto Opposition (MoPlO) was topmost. In North Saurashtra zone or Zone-6, the predominant planetary combination for extreme rainfall was 23 for Rajkot and 14 combinations for Dwarka. The topmost combination was Moon-Pluto Opposition (MoPlO) for Rajkot and Moon Neptune Kranti Pratiyuti (MoNeKp) for Dwarka. In South Saurashtra zone or Zone-7, the predominant planetary combination for extreme rainfall was 22 for Junagadh and 21 combinations for Veraval. The topmost combination was Moon-Jupiter Kranti yuti (MoJuKy) for Junagadh and Moon-Neptune Kranti Pratiyuti (MoNeKp) for Veraval. In Bhal and Coastal zone or Zone-8, the predominant planetary combination for extreme rainfall was 16 for Bhavnagar and Arnej. The topmost combination was Moon-Mars Conjunction (MoMaC) for Bhavnagar and Moon-Mercury Kranti Pratiyuti (MoMeKp) for Arnej. For prediction of extreme rainfall, the three planetary combinations, viz., Moon-Mars Kranti yuti (MoMaKy), Moon-Saturn Kranti yuti (MoSaKy) and Moon-Mars Kranti Pratiyuti (MoMaKp) appeared in 13 stations out of 16 stations (81.25%). In total, there are 28 combinations in the state model whose appearance ranged from 43.75 to 81.25%. In extreme rainfall, validation results revealed that the literature model showed 23.0% accuracy while, station model showed 52.6% and the Gujarat state model showed 69.2% accuracy. The aspects between Saturn, Mars and Moon create cyclones and heavy rainfall which is in confirmation with our results in case of extreme rainfall in 13 stations of Gujarat. Also, certain positions of the Moon with Jupiter / Saturn bring scattered but heavy showers conforming to our study made in Gujarat as reported by other previous workers.
VARAHAMIHIRA: A PIONEER OF INDIAN METEOROLOGY
The formulas for predicting rainfall, developed over 1500 years ago by Varahmihira (who lived in or around Ujjain in present day Madhya Pradesh in the sixth century CE), remain relevant today. His observations on the behaviour of clouds, winds and stars formed the basis for weather forecasting in ancient India. Varahamihira emphasised the importance of observing natural phenomena and combining these observations with mathematical calculations to achieve accurate predictions. The Brihat Samhita, one of Varahamihira’s most celebrated works, contains a wealth of information on meteorology. It addresses the phenomenon of rainfall across eight chapters, drawing parallels with the conception, pregnancy and delivery of clouds over a period of 195 lunar days, using asterisms like Rohini Yoga, Swati Yoga and Ashadha Yoga. Additionally, the treatise offers meteorological insights on topics such as halos around the sun and moon, cloud formations, winds, red skies before sunrise and after sunset, dust storms, thunderbolts, astronomical events like meteor falls, among others.
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LONG-RANGE FORECASTING IN BRIHAT SAMHITA
The seasonal rainfall forecasting was done by using Varahmihira’s model. The dates of Jyeshtha Purnima were considered from Date Panchang Pune (MS). The rainy day (rainfall equal to or more than 2.5 mm) after Jyeshtha Purnima date in all 16 stations was found from 1969-2018. As per verses 6-9 of Chapter 23 of Brihat Samhita, the prediction of seasonal rainfall was derived from the Chandra Nakshatra of the first rainy day after Jyeshtha Purnima of each station. The Chandra Nakshatra of that rainy day was also noted from old versions of Date Panchang, Solapur (MS) for the period from 1969-2018. The value of seasonal rainfall given in old units of drona was converted to modern day units as 1 drona = 6.4 cm = 64 mm rainfall.
Varahmihira made 10 classes of seasonal rainfall based on 10 groups of Chandra nakshatra (out of a total of 27 nakshatras) of days of the first rainy day after Jyeshth Purnima which is similar to the start of the rainy season. The seasonal rainfall prediction (mm) was done for each location from 1980 to 2018 using Varahmihira’s hypothesis. The validation was also done with actual observed rainfall for 16 locations (2 each from 8 agro-climatic zones of Gujarat). Validation of Varahmihira’s model revealed that this model can be used for forecasting station’s seasonal rainfall where average percent error was lower than 10% (like Junagadh, Anand, Godhra and Bharuch) and state’s average rainfall prediction since average error of state’s rainfall prediction was -7.9%. The study in Tirupati (AP) revealed that the annual rainfall predicted based on planetary ruler of year (in local panchang of Tirupati in Andhra Pradesh) and qualitative rainfall prediction was compared with actual observed annual rainfall at Tirupati. The percentage of agreement for the South-West monsoon season ranged from 10.6% to 72.8% with the mean value of 37.5%. In Gujarat, the average CV of seasonal rainfall is nearly 50% hence lowest rainfall stations like Bhuj, Nalia, Idar and Dwarka showed more errors. In high rainfall stations like Valsad and Navsari, the prediction was lower as compared to observed rainfall. Thus, Varahmihira’s model is consistent with the current understanding of rainfall distribution.
Thus, from the above studies made by me in Gujarat as part of PhD research, we can predict extreme rainfall from planetary combinations for each station and also predict station’s seasonal rainfall by using Varahmihira’s model. Similar intensive studies can be carried out for other states for deriving predictions of extreme rainfall and seasonal rainfall. We can put ancient wisdom in operational use for the benefit of farmers in particular and people in general.
*Dr Vidyadhar B Vaidya is Assistant Professor of Agricultural Meteorology in the Department of Agricultural Meteorology, BA College of Agriculture, Anand Agricultural University, Anand. He is also a member of the executive committee of Gujarat Council of Science City, DST, Government of Gujarat. Suvarna Dhabale is Research Associate, Department of Agriculture Meteorology, BA College of Agriculture, Anand Agricultural University, Anand.
