Parts of eastern India, including Bihar, Jharkhand and Odisha, are likely to face above-normal temperatures in May with a likelihood of heat wave conditions on some days, the weather office has said.

However, parts of northwest and west-central India may experience warmer nights and below-normal temperatures during the day, the India Meteorological Department said in the monthly outlook for temperature and rainfall for May.

It said normal to above-normal rainfall is expected in the northwest and west central parts of the country in May, including in Punjab, Haryana, Rajasthan and parts of western Uttar Pradesh. Large swathes of the northeastern region, Kerala, Andhra Pradesh and south Karnataka, are expected to witness below-normal rains.

According to the weather office, the average rainfall in May is likely to be 91-109 per cent of the Long Period Average of 61.4 mm.

"Above-normal heat wave days are expected over most parts of Bihar, Jharkhand, Odisha, Gangetic West Bengal, east Uttar Pradesh, coastal Andhra Pradesh and some parts of North Chhattisgarh, east Madhya Pradesh, Telangana and coastal Gujarat during May," IMD Director General Mrutyunjay Mohapatra said here.

He said the neutral El Nino prevalent over the equatorial Pacific region is expected to continue through May with a majority of weather models indicating the region beginning to warm up during the monsoon season.

El Nino, or warming of the equatorial Pacific Ocean, is said to have an impact on monsoon rains in India. However, other factors such as the sea surface temperatures in the Indian Ocean (known as the Indian Ocean Dipole) are also known to influence the weather.

Mohapatra said the neutral IOD conditions prevailing over the Indian Ocean are likely to turn positive during the upcoming season. He said positive Indian Ocean Dipole conditions are known to favour the Indian monsoon and help temper the impact of El Nino.

Earlier this month, the IMD forecast a normal monsoon season with 96 per cent rainfall of the Long Period Average of 87 cm rainfall. The weather office is expected to update its forecast towards the end of May.

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