I have a Planet bike 2 watt front light and a couple back lights also by PB, and I was wondering, is it ok to ride in the rain with them? Thank you.

There have been many reports of PB blinkies failing in the rain. I've used mine several times in torrential downpours, but you never know. :-)

I currently have a P7 flashlight on my helmet.
But I've used a PB Blaze 1/2 watt for many years
in all kinds of weather. Other than the threads on
the handlebar mount rusting a bit, no problems.
No weather related issues on my PB Superflash,
also a few years old.

No problem with my Dinotte L200 while in lots of rain during the past several years. My PB blinky I have on the back as a back up has not faried as well.

Most of the time a "trace" amount of water will get inside any light that needs to be opened to insert a battery. And unfortunately, unless you reopen and let the light and battery compartment dry out - corrosion can form. This doesn't happen every time - but sooner or later most lights that are used repeatedly in the rain will sustain damage. Of course - as long as it take a couple of years - who cares?

My 1 and 2W Blazes have been fine in the occasional rain I've ridden in. I put a very very thin film of silicone grease on the seals of my lights and other electronic equipment exposed to water as is done for scuba lights, underwater camera housing, etc.. This improves the seal but also creates a hydrophobic surface which helps repel water. As mentioned by others, if you suspect any water or condensation has gotten in, open the light and let it dry out. Gentle warming, like sitting on top of your water heater, etc. will help, especially if it's very humid.