[BRENT in 10-uh-C]

Too high idle speed or too thin of lube. Generally speaking you can slide it into 3rd gear first and then quickly move it into 1st gear while stopped. Since you stated it won't go into any gear, this suggests the clutch disc is unable to release completely. My first step would be to see if you can start the engine with it into a gear and the clutch pedal depressed. Do this when engine has been warmed up. This should tell you if the clutch can be disengaged. Humidity really should not matter unless the flywheel clutch surface as become rusted.

You did not mention if the clutch or flywheel have been worked on during this time. If not, it is possible. The clutch disc is installed backwards.