The Britain-based monitor said those killed in the strikes, on three locations in the province, were mostly civilians.
The Observatory says it determines whose planes carried out raids according to their type, location, flight patterns and the munitions involved.
The toll included 26 civilians, among them three children, killed in the town of Kafr Nabal, and another 18 people who were killed in the town of Maaret al-Numan.
In Kafr Nabal, an eyewitness told AFP that warplanes carried out several strikes.
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In Maaret al-Numan, an AFP photographer saw local residents and White Helmets rescue workers trying to reach survivors in the rubble at a vegetable market hit in a strike.
The Observatory said most of those killed in Maaret al-Numan were civilians, but that the identities of four of the dead were still being confirmed.
The monitor also reported two additional deaths, one in an earlier strike on Maaret al-Numan and another in Al-Naqir, also in Idlib.
And it said six civilians, four of them children, had been killed in a government barrel bomb attack on the town of Al-Tamanah in the south of Idlib.
It has dismissed reports of civilian casualties in its strikes and says it only target militants.
In November, Defence Minister Sergei Shoigu said Russian forces had begun a "major operation" targeting Idlib and Homs provinces.
Idlib province is mostly controlled by a powerful rebel alliance known as the Army of Conquest, which groups Islamist factions with jihadists of Fateh al-Sham Front, formerly Al-Qaeda's Syrian affiliate.
Most of Homs province is controlled by the Syrian government, but small parts of the countryside in the region are held by a range of rebel groups.