Commemorations in the Coptic Orthodox Diocese of Minya will be limited to liturgical prayers "without any festive manifestations", following blasts in Tanta and Alexandria.
At least 28 people died at St George's Church in Tanta, while another blast at St Mark's Cathedral in Alexandria claimed at least 17 lives.
Minya has the highest Coptic Christian population of any province in Egypt.
The explosions on Sunday follow a suicide bombing at a chapel next to St Mark's Coptic Orthodox Cathedral in Cairo on 11th December 2016.
Islamic State claimed responsibility for the two explosions on Sunday, which represent an escalation by the extremist group, which has vowed to increase its attacks against Egypt's persecuted Christian minority.
A three-month state of emergency declared by Egypt's President Abdel Fattah el-Sissi came into effect at 1pm on Monday.