Tungsten Halogen Globes
Due to high-temperature glass (4000 ‘F filament). Any dust, finger-skin-oil, can cause thermal stress or water drops can cool glass, lower resistance and draw more current blowing fuse or excess heat in a closed enclosure with reduced life span will sputter tungsten inside the glass when it fuses open. 

I’m surprised the glass didn’t break, if it got wet, but perhaps it didn't and rain was coincidental.  Start current  when cold is 3kW and steady  state hot is 300W.  Divide by /x for lower power bulbs but all tungsten filaments are about 10:1 cold:hot resistance and power consumption.

It's a fact that lifespan of any tungsten bulb can be extended greatly by even cooling it 50 to 100'C degrees down inside the luminaire for convection air flow.