hi guys im new to this forum.

my haonda accord's temp gauge used to always below 1/2 in the dashboard.

lately ive been relizing that sometimes it starts going up all the way up to 3/4 and after couple of minutes (sometimes more) drops back to where it should be below 1/2.

can anyone tell me wat i need to check.
already checked the water coolant level and its full, im pretty much sure i dnt have leak.

thank you in advance
sergio