of the year, on average, is January; April and May are the warmest months. Average temperatures in January range from , and average temperatures in April range from . July is on average the coldest and wettest month: over of rain falls on the delta. Arid and semi-arid regions A tropical arid and semi-arid climate dominates regions where the rate of moisture loss through evapotranspiration exceeds that from precipitation; it is subdivided into three climatic subtypes: tropical semi-arid steppe, arid climate, tropical and sub-tropical steppe climate. 1) A tropical semi-arid steppe climate (Hot semi-arid climate) predominates over a long stretch of land south of Tropic of Cancer and east of the Western Ghats and the Cardamom Hills. The region, which includes Karnataka, inland Tamil Nadu, western Andhra Pradesh, and central Maharashtra, gets between annually. It is drought-prone, as it tends to have less reliable rainfall due to sporadic lateness or failure of the southwest monsoon. Karnataka is divided into three zones – coastal, north interior and south interior. Of these, the coastal zone receives the heaviest rainfall with an average rainfall of about 3,638.5 mm per annum, far in excess of the state average of 1,139 mm (45 in). In contrast to norm, Agumbe in the Shivamogga district receives the second highest annual rainfall in India. North of the Krishna River, the summer monsoon is responsible for most rainfall; to the south, significant post-monsoon rainfall also occurs in October and November. In December, the coldest month, temperatures still average around . The months between March to May are hot and dry; mean monthly temperatures hover around 32 °C, with precipitation. Hence, without artificial irrigation, this region is not suitable for permanent agriculture. 2) Most of western Rajasthan experiences an arid climatic regime (Hot desert climate). Cloudbursts are responsible for virtually all of the region's annual precipitation, which totals less than . Such bursts happen when monsoon winds sweep into the region during July, August, and September. Such rainfall is highly erratic; regions experiencing rainfall one year may not see precipitation for the next couple of years or so. Atmospheric moisture is largely prevented from precipitating due to continuous downdrafts and other factors. The summer months of May and June are exceptionally hot; mean monthly temperatures in the region hover around , with daily maxima occasionally topping . During winters, temperatures in some areas can drop below freezing due to waves