Can i leave my PC in humid temperature?

Why leave it on if you are not going to be there? Here is some information.

Humidity and Computers

Craig Borysowich Feb 15, 2005
Environmental conditions – especially humidity – can directly affect the functioning and performance of computers…

"A high level of humidity can cause internal components of PCs to rust and degrade some of their essential properties, such as electrical resistance or thermal conductivity. Under extreme conditions, humidity can cause computers to short-circuit, resulting in effects ranging from loss of data to physical damage of some system components. This situation can be aggravated further when computers are in environments that are not climate controlled such as warehouses or areas on industrial floors where other chemical vapours may be mixing with the humidity and becoming corrosive.

Computers are usually used in environments with an acceptable level of relative humidity, such as offices where conditions are controlled through air-conditioning systems. However, the same cannot be said for mobile devices or laptop computers, which can sometimes be exposed to extreme conditions. One of the most common problems is liquid getting into computers from rain, water splashed on a laptop when using it at the beach or near a swimming pool, or drinks that are accidentally spilled on them.

However, humidity can also condense inside the computer without the user realizing. This often happens when the computer is exposed to brusque changes in temperature. A typical example is when a computer is used in an air-conditioned office immediately after being transported in a vehicle exposed to direct sunlight. The same effect happens when walking for a distance outside during the winter, and then bringing the computer into a warm office – A thin film of condensation could be covering the entire interior of the laptop.

The basic measures to take in order to prevent excess humidity that can damage PCs include not using computers near liquids or where liquid can be splashed on them and not exposing them to extreme humidity. Similarly, it is also advisable to avoid brusque changes in temperature and wait for your equipment to adapt to their new conditions before switching them on. Relative humidity levels between 45% and 60% are best for computing environments. Laptops may be able to go to a more extreme 30%-80%, but never use a computer beside or near an actual humdifier."
http://it.toolbox.com/blogs/enterprise-solutions/humidity-and-computers-3158

I don't know what you mean by really humid, it's summer where I'm at and humidity is rarely below 40-50%. It can often get up to 70-80% or worse. It will probably be fine. Liquid spills and rain water are vastly different than humidity.

Unplug it and it will be fine no possible of short circuit that way

Unplug your computers, and let the turn the A/C on and let your place cool down before starting up your cpu.