Not good, to be frank. One of my cats (Kika) is missing since Sunday. We've already looked for her around, asked the neighbours, contacted the local vet... nothing.
What worries me the most is that it'll rain today.
Thank you, mate. And good news - in the meantime, we found her! I had to trespass into someone else's property (it's an extended holiday here, so a lot of people are travelling), but got her back. Besides the thirst and hunger she seems OK, not injured. (Unlike my arms - she kicks a lot when held on arms, and she was scared so... ah, nothing that rubbing alcohol + a few days won't solve.)
I don't know if it will work for you, hope it does. If your cat uses a litter box, take a hand full, ideally not new, and dump it in front of either your door, a place that Kika can come in and out from, or a place where you would see her.
The smell of their own... box helps them find the way home, according to my vet.
The idea is rock solid though. Specially because one of my fears was that it rained today, so it erased all smells that she could rely on. (And the fact that she's 15yo, her senses aren't exactly the same of a young kitten any more.) So any smelling/visual/auditive clue helps.
She was hiding in the yard of someone else's home. It isn't too far from my own home, but she's indoors, old, and scared of her own shadow, in a street with lots of barking dogs. So she was having a really hard time coming back.
Retrieving her was a bit of a mess, since the houseowner wasn't home* I had to jump into his yard from his neighbour's yard. (They even lent me their ladders!) Now back home she ate a lot, drunk a lot of water, and now she's calling me every five minutes because she's really needy.
*acc. to the neighbours he went to the beaches. This week has an extended holiday, so he'll probably only come back tomorrow, or even after tomorrow. So I didn't want to risk her roaming elsewhere.