Well, the calendar is updated with the best thrash and death metal shows in San Francisco and the East Bay for the first half of 2025 -- at least what has been announced so far. (The genres can be argued but are mostly on the more extreme side of metal, plus any great local metal bands. Nothing too commercial or nu).
There are a lot of great shows coming up, but April is particularly insane:

You could start your April seeing heavy metal 5 nights in a row just in Oakland and San Francisco:
April 5-9, 2025
Machine Head / In Flames
Haunt
Napalm Death / Melvins
Meshuggah / Cannibal Corpse / Carcass
Mayhem / Mortiis / Imperial Triumphant
You have some constitution if you can make it to all those (or you are rich, unemployed, and don't drink).
Then you finish up the month spending your weekend at the UC Theatre in Berkeley:
April 25-27, 2025
Friday: Exodus / Death Angel / Blind Illusion
Sunday: Obituary / Nails
I know I'm not missing that last weekend. Will have to see how many of the first run I get to, other than the Melvins who I try never to miss (especially at the great Great American Music Hall).