Terrorists and militants carried out 65 attacks, including two suicide bombings, across Khyber-Pakhtunkhwa and the Federally Administered Tribal Areas, data collected by the Edhi rescue service showed.
Besides the 91 people killed, another 225 were injured in the incidents.
The figures do not take into account deaths in attacks in the Waziristan tribal region, a safe haven for Taliban and Al Qaeda elements.
Militants also damaged four girls' schools last month, which experts said was a setback for the province and tribal areas since the female literacy rate in these areas is only 33 per cent and 10.5 per cent, respectively.