The hot weather period this summer is the worst in the last five years in Andhra Pradesh and Telangana.

The number of heatwave days has increased from the normal 15 to 24 days in coastal Andhra Pradesh. In the Rayalaseema region, the number has increased from 0-5 days to 13 days.

Severe heatwave conditions have prevailed at isolated places for five days each in Krishna and Guntur districts. The delay in the advancement of the southwest monsoon in the two States has resulted in the hot weather conditions extending up to the third week of June. These are the findings of an analysis made by P.V. Rama Rao, a retired Director of the India Meteorological Department (IMD), based on the day-to-day weather data and weather maps collected from the IMD websites. South coastal Andhra Pradesh and Godavari districts are prone to heatwave. Similarly, Guntur and Krishna districts are prone to severe heatwave conditions. The north Andhra districts of Srikakulam, Vizianagaram and Visakhapatnam are comparatively less prone to heatwave conditions. Though Rayalaseema too is less prone to heatwave conditions, it experiences hot weather with the maximum temperatures varying between 39° Celsius and 44° Celsius.

Temperature changes

“Normally, a trough of low pressure exists over the States during summer. The axis of the trough line usually extends from Chhattisgarh to south Tamil Nadu across A.P. or Telangana, and it is more pronounced from April. Temperature changes are caused by changes in pressure distribution and shift in the trough line towards the areas of falling pressure and shift towards east or westwards from its normal position. This is the main reason for changes in the maximum temperature,” explains Mr. Rama Rao.

When the trough line passes across Telangana and Rayalaseema, all inland stations experience hot dry winds and coastal areas experience relatively cool weather due to flow of moist winds from the sea. When it passes across coastal A.P., stations located to the left of the trough line experience hot weather and those to the right relatively cool weather.

When the trough line passes over or lies along and off the Andhra coast, the flow of moist winds from the sea is arrested and, in its place, hot dry north-westerly winds from Central India extend over the coast.

In such a synoptic situation, both the States experienced heatwave conditions on May 3, when the extremely severe cyclonic storm ‘Fani’ crossed the south Odisha coast. In coastal A.P., there was delay in the foray of the southwest monsoon by 20 days and in coverage by 11 days, whereas in Rayalaseema the delay was 20 days and in coverage by 16 days.

Hence, the hot weather in A.P. was extended up to the third week of June.