Since the volume is constant but the pressure and temperature are changing, this is an example of Gay-Lussac's Law:
$color(blue)(bar(ul(|color(white)(a/a) p_1/T_1=p_2/T_2color(white)(a/a)|)))" "$
We can rearrange the above formula to get
$T_2 = T_1 × p_2/p_1$
Your data are:
The new temperature is 627 °C.