Temperatures above 50 Celsius (122°F) last week caused a spike in heatstroke and triggered power cuts as demand surged

NEW DELHI, May 23 (Reuters) - India was bracing on Monday for another bout of extreme heat after temperatures smashed records in some parts of the country, while weather officials warned against more frequent heat waves.

Temperatures in parts of the western region breached 50 Celsius (122°F) last week, causing a spike in cases of people suffering dehydration and heatstroke, and triggering widespread power cuts as surging demand overwhelmed supply grids.

Television channels in Gujarat state showed residents struggling to cross a street as their shoes became stuck in what appeared to be the melting surface of a road.

May and June are typically India's hottest months, when temperatures regularly exceed 40 Celsius in the run-up to the monsoon rains, but the severity of the heat this year has caught many off guard.

"There are usually thunderstorms this time of year, but these rains have not been occurring," said B.P. Yadav, head of the national weather forecasting centre of the India Meteorological Department.

"Hot winds have been blowing in from Afghanistan and Pakistan, leading to these extreme temperatures."

The mercury hit a record 51 degrees Celsius last week in Phalodi, a city in the western desert state of Rajasthan, beating a previous national high of 50.6 degrees in 1956.

The heat should ease with the arrival of clouds and light showers this week, Yadav said, but his office forecast a return to elevated temperatures in late May or early June.

Possible reasons for the rising temperatures ranged from global warming to greater urbanisation, leading to taller buildings and increased pollution, Yadav added.

The heat wave has struck as India grapples with a major drought, worsening water shortages that have hit an estimated 330 million people.

"We are praying to the gods for an early monsoon so that people get some relief, as the heat has taken a toll on our bodies," said Neeraj Kumar, a resident of the northern industrial city of Kanpur.

"We are not even able to do our daily chores properly."

The number of heat waves had nearly doubled in the 10 years to 2010 from earlier decades, the meteorological office said. The number in the last six years had also risen from prior to the year 2000, but identifying clear trends requires more data.

In January, two U.S. government agencies said last year's global average temperature was the hottest ever by the widest margin on record. (Reporting by Tommy Wilkes; Additional reporting by Reuters TV; Editing by Douglas Busvine)

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