Three bomb blasts in the state capital Maiduguri around 7:30 p.m. (1830 GMT) left at least 54 people dead and 90 injured. Around two hours later, two bombs exploded at a checkpoint some 135 km away at a market in the town of Monguno.
Locals residents and a hospital source said that attack killed 27 people and injured 62 others.
No one has claimed responsibility for the attacks but they bore the hallmarks of the jihadi sect, which has been trying to carve out a state in the northeast of Africa`s most populous country since 2009.
"A suspected Boko Haram suicide bomber detonated IEDs (improvised explosive devices) at a mosque in Ajilari and some insurgents also threw IEDs at a viewing center," Victor Isuku, a police spokesman in Maiduguri, said of the first attacks.
"Total casualty figure is now 54," he said.
A Nigerian army spokesman said on Sunday that three bombs had gone off.
Local residents said a suicide bomber hit a market at Monguno, killing at least 27 people.
"I counted 27 dead bodies from the scene," said Malum Sunoma, a local resident who helped with rescues. He was speaking on the phone from a hospital where his brother was being treated.
"Five vehicles conveyed 62 injured persons from the Monguno attack to the specialist hospital in Maiduguri," said a doctor, who spoke on condition on anonymity.
The Boko Haram insurgency has killed thousands and displaced 2.1 million people.
Buhari`s March election victory owed much to his vow to defeat the insurgents, but there was a spike in attacks across northern Nigeria in the two months following his inauguration and Maiduguri was hit on a near weekly basis.
A new offensive launched by the Nigerian army to clear Boko Haram out of more towns over the last month has led to a sharp drop in the frequency of attacks in Borno, the worst affected by the insurrection, and neighboring states.
Maiduguri has been free of attacks for about a month. It was last hit by a bomb at the end of July and there was a skirmish with suspected Boko Haram militants on the outskirts of the city in mid-August.
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