The mercury soared to a maximum of 47.2 degrees Celsius in Allahabad Thursday, an official said on Friday.
Met officials said the heat is likely to continue for another one week after which the monsoon is set to arrive in the state. Mahoba was the hottest place with 48.1 degrees Celsius.
The state capital also set a new high of 46 degrees Celsius, breaking a decade-old record.
J.P. Gupta, director of the regional Met Office, told IANS there will be no respite in day temperatures.
The official said the maximum temperature in Barabanki and neighbouring Lucknow was 47 degrees Celsius, while in Agra it was 46.5, followed by 46.2 in Hamirpur, 46 in Rae Bareli, 45.5 in Shrawasti and 45 degrees Celsius in Bahraich.
Two people died due to heatstroke Thursday evening in Mainpuri in central Uttar Pradesh, officials said.
What added to the summer woes for residents is the severe power crisis, with many cities and towns witnessing power outages of 16-18 hours daily.
At many places in the state capital, very low voltage made the night unbearable and angry residents took to the streets and vent their ire on powermen.
A power official told IANS there has been a slight improvement in the state's power pool as the central government has released 400 MW for UP and that the gap between the supply (12,000 MW) and demand (14,000 MW) had come down to 2,000 MW from 3,600 MW a few days back.
The official, however, admitted the crisis was far from over.