Joint director, vector-borne diseases, Vikas Singhal, said that more than 4,000 dengue cases had been reported in the state since January.
Of these, the maximum is from Lucknow, followed by Kanpur (700) and Allahabad (325).
More than 90 percent of the cases have been reported in the Monsoon season since July.
Singhal said that the number of cases is expected to decline from the third week of November when the maximum temperature will go down below 25 degrees Celsius. Till then, he added, people will have to take precautions. The health department, he said, is already carrying out a massive anti-mosquito exercise.
The disease has also claimed six lives so far -- four in Lucknow and one each in Unnao and Barabanki.
According to experts, the number of cases is high in Lucknow and Kanpur mainly because of diagnostic and treatment facilities and the influx of patients from adjoining districts.
"There is a possibility of cases going unreported in rural areas. The health department has not been able to enforce the rule for private labs and clinics in these areas to report cases to the chief medical officer," said D. Himanshu, associate professor in the department of medicine at King George's Medical University.