Has anyone put his Nikon D90 to a grueling weather test so far and survived? Like Nikon service warranty, its always not clearly stated as to how much can the camera take before crumbling into malfunctions.
The bigger sibling Nikon D300 (see image above) has withstand hell but a more preventive approach should be adopted for the Nikon D90. [Fotosharp] recommends a "rain coat" and it looks interesting. While some others simply recommend a conventional zip-lock bag packed with silicon!
Well, I guess as long as its operating within the 0-40 Degree Celsius / 85% humidity boundary, you should be fine. Here's the [comment] from some users about their Nikon D90.
Basic Tips - Always remove your battery from the camera during cold transport and keep it close to your body (warm).