I'm interested in hearing first hand experiences of people using these PIR sensors outdoors, especially in colder climates.
Basically wondering if these things are operable in Wisconsin winters, say -10 F
I don't have experience with your question but I would say that as long as the electronic part of the sensor is protected (the white dome could probably be left out) you're good. I don't know if the temperature would affect the output (I don't think so) but I'd say just give it a shot. The sensors are dirt cheap.
Condensation would be the killer.
You could try a decent conformal coating or if you could seal the dome to the board with say neutral cure silicone, the delicate bits could go into an IPx8 enclosure with a bag of silica gel desiccant.
Maybe easier, might be to encapsulate everything with an epoxy (except the dome) and that would seal any leads as well.
I sometimes use a hot melt glue to coat the lot.
If it's kept dry so that volts don't track where they aren't wanted, they should last.
As an afterthought, they ought to work well in detecting a heat source against a -10F background, so that would be a bonus.
I would also worry that the white plastic cover will become brittle and crack when exposed to UV- it doesnt look very thick.
debum:
...the white dome could probably be left out..
Not just a dome. It's a Fresnel lens.
Sensor won't work without it.
Leo..
Put an O-ring on the sensor and mount from the inside of the box. Make sure the box is rated for being waterproof. Seal all cable entry/exit with silicon or better water sealer.
Should last a good few years. For the price of those sensors, that' not bad!
rw950431:
I would also worry that the white plastic cover will become brittle and crack when exposed to UV- it doesnt look very thick.
Its probably polythene which is likely better than many polymers against UV radiation. It
has to be a polymer transparent to infra-red which rules out most possibilities - no active
groups basically which also confers inertness to UV. Still years of sunlight trash most
polymers...
For outdoor use a conformal coating on the PCB would be good - keeping the moisture off.
It should work in the cold, however, on a nice warm day (around 90 degrees F or so), people and other "warm" bodies become basically invisible to it since everything is the same temperature. Ran into that a while back when I wanted to find out who was going in our yard during the day. Ended up using a modulated IR beam instead 
gpsmikey:
It should work in the cold, however, on a nice warm day (around 90 degrees F or so), people and other "warm" bodies become basically invisible to it since everything is the same temperature. Ran into that a while back when I wanted to find out who was going in our yard during the day. Ended up using a modulated IR beam instead
The OP said "Basically wondering if these things are operable in Wisconsin winters, say -10 F"