Legal Question in Landlord & Tenant Law in California

I'm not sure where you get the concept that there is a "required 30" days to terminate a lease before it expires. Unless your lease has a provision allowing you to break it early on 30-days notice (which would make it essentially a month-to-month tenancy, not a true lease) you are obligated to pay rent for the full term. Failure to do so is a breach of the lease whether you move out or not.

With that said, whenever a party to any kind of contract breaches it, the other party has an obligation to mitigate their damages, and if possible eliminate them. So if DelMonte suddenly decides it doesn't want the 200,000 lbs of tomatoes it contracted to buy from a farmer, the farmer must try to re-sell them, and he is free to do so at a higher price than DelMonte was supposed to pay, but he can't just let the crop rot while holding out for a higher price. The farmer must act in a "commercially reasonable" manner in trying to resell the tomatoes.

Your landlord is the farmer and your apartment is a load of tomatoes. Your landlord is free to try to get a higher price for the unit, but not at the cost of losing money that they then expect you to pay. The problem is that "commercially reasonable" depends on all the facts and circumstances of the situation, and that's the stuff that litigation is made of.

Being a renter of a place in San Francisco during the week, I am familiar with the insane explosion of rents here. A 65% increase, however, seems pretty over the top unless you have been living there a long time and are under rent control, particularly if truly comparable units are going for $1,000/mo less. You don't get very far, however, with how long it took them to list it. Tenants generally want to move in a 30-day window, so listing a unit way before it will be available doesn't do much good.

The last thing both you and the landlord need to bear in mind is that if the landlord DOES manage to rent the property for $1,500/mo more than you are paying, the landlord recoups a month of vacancy for every roughly 1.5 months the new tenant is paying the new rent. On the one hand that plays to the landlord asserting they are acting in a commercially reasonable manner, and on the other hand it plays to your side in that it would wipe out their damages, but do you really want to play into that risk?

The bottom line is that the landlord is simply wrong if they think they can hold out for whatever rent they want and charge you for the lost rent during any vacancy, especially if they think they can get away with not crediting you back for the increased rent against what they charge you for the vacancy, once they get the higher rent. But on the other hand, you are breaching a contract and that entitles the landlord to damages for lost rent during a commercially reasonable vacancy. Unless you both want to wind up in court, you need to work out some kind of lease termination agreement taking these concepts I have discussed into account.