Wipe the inside and outside of the glass with a dry cloth. If the haze stays put, it's trapped between the panes. That confirms a failed seal.
Snap a photo in the morning when marine fog rolls in and again on a warm afternoon. The moisture usually looks heavier when it's cool and damp, which helps the glazier size up the failure.
If you can, jot down the width and height of the visible glass. It speeds up ordering the right insulated unit.
Don't try to pry the panes apart or drill a drain hole. It won't clear the fog and it can crack the glass.
That cloudy look between the panes comes from a broken seal on your insulated glass unit, or IGU. Two panes are bonded with a spacer and sealed to trap dry air or gas in the middle. Once that seal cracks, humid air sneaks in, and Monterey's damp coastal air gives it plenty to work with. Morning fog off the bay and salt in the air are hard on window seals over the years.
A glazier will confirm the fog is truly between the panes, then check the frame and spacer for rot or corrosion. In older homes around Downtown and East Monterey, the wood sashes sometimes need attention too. The good news: in most cases you replace just the glass unit and keep your existing frame, so it's a cleaner job than a full window swap.
It's not an emergency, but don't sit on it forever. A failed seal means you've lost the insulating gap, so that window lets more heat and cold through and can start to spot or stain. If the glass is also cracked or the pane feels loose, call sooner. Trapped moisture near wood framing in places like Berry Hill or Green Hills can lead to soft spots if it drags on.
Describe what you're seeing to a real Monterey glazier: call (615) 555-0195 or send the form. Free, no obligation.