Earlier, yellow warning of heavy rainfall was issued in 20 districts of the state on Thursday.
The weather system is set to form over north Bay of Bengal around Friday under the influence of a cyclonic circulation, which lies over south Myanmar, the Bhubaneswar Meteorological Centre had said in a bulletin on Wednesday.
The meteorological center issued an orange alert of very heavy downpour of 116-204 mm in 17 districts, including Cuttack, Kendrapara and Sambalpur, on Friday. Heavy showers are expected for the rest of the 13 districts on the day.
It also predicted very heavy precipitation in Kalahandi and seven districts of western Odisha on Saturday, besides heavy rain in nine adjoining districts.
The government has advised fishermen not to venture into the sea in north and west central Bay of Bengal on Friday and off the coast on Saturday as squally weather with wind speed of 45-55 km per hour is expected over the region, officials said.
Odisha Chief Minister Naveen Patnaik on Thursday also made an aerial survey of five of the 12 flood hit districts of the state and announced succour for the affected in the calamity for the next 15 days.
Patnaik made an aerial survey of the Mahanadi delta area falling between Luna, Chitratola and Paika rivers in Kendrapara district, Kujang and Naugaon in Jagatsinghpur district, Gop, Nimapara, Astarang, Delang, Pipili and Kanas areas of Puri district.
He announced relief to the people of flood affected villages of the worst hit districts of Khudra, Puri, Cuttack, Kendrapara and Jagatsinghpur for 15 days.
The chief minister also announced relief for seven days for the people of the flood hit areas of Sambalpur, Bargarh, Sonepur, Boudh and Angul districts, which are all located in the upstream of river Mahanadi.
Both cooked and dry food, candles, matchboxes, drinking water pouches, medicines, baby food and other essentials will be provided to the flood victims by the government, he said.
Expressing concern over the inundation of the populated areas in the Mahanadi delta region in which many farmlands and houses have been damaged, Patnaik directed officials to expedite relief work, provide cooked food, healthcare service and supply drinking water to the people of the affected areas.
He asked the department concerned to provide fodder and treatment to the cattle in the region.
Patnaik also directed the districts' authorities to undertake damage assessment within seven days of the water receding from the villages and provide assistance to the affected people within 15 days.
Around five lakh people in 12 districts are reeling under the flood caused by the Mahanadi river after incessant rains lashed the state last week in the wake of a low pressure and a subsequent depression.
There were reports of two minors missing in Cuttack and Balasore districts. The flood-hit districts are Angul, Bargarh, Boudh, Cuttack, Jagatsinghpur, Jajpur, Kendrapara, Khurda, Nayagarh, Puri, Sambalpur and Subarnapur.
With the rains letting up in the upstream of Mahanadi river in Chhatisgarh 12 of the 40 gates of Hirakud dam were closed, special relief commissioner P K Jena said. The reservoir level will be brought to 622 feet by 9 am on Friday, he added.
In view of the flood, Odisha Public Service Commission on Thursday also postponed the written examination for recruitment of assistant section officers. The move came as a huge relief to thousands of job aspirants, who have been demanding that the examination slated to be held on Sunday be postponed.
The rescheduled date and time will be notified soon, the order by the Commission said. The state government has closed schools in many flood affected areas, School and Mass Education Minister Samir Ranjan Dash told reporters here. All government and private schools in Puri district which were earlier ordered to be closed till August 18 will remain so for two more days. The Nayagarh district administration had also ordered closure of 32 schools in three blocks for two days due to the flood situation.
Meanwhile, water resource department chief engineer B K Mishra said there are seven breaches on the embankments of the Mahanadi river and its tributaries and workers have been deployed to repair them.
With the flood inundating over 1,757 villages and 10 urban areas, the state government has strengthened rescue teams of the National Disaster Response Force, Odisha Disaster Rapid Action Force and Odisha Fire Service, officials said.
(With inputs from PTI)
