After a slight decrease from severe levels, the mercury is hovering around 40 degrees Celsius in most regions
He was arrested on Thursday night from Demra area.
The June 15 attack on Najimuddin College maths teacher Ripon Chakraborty had failed and people managed to apprehend assailant Faizullah Fahim. The assailant died three days later in police custody, in a so-called crossfire between police and terrorists.
Fahim is believed to have been a member of banned terror group Hijbut Tahrir.
Police are yet to ascertain if Saifullah had the same links.