Long shorts are okay for men as long as the beach look is avoided. Autumn days are mild, but there might be a chance of rain - rain wear advisable. Regardless of season men are best off in dark coloured suits with a blue or white shirt. Other colours are worn, but blue and white are considered the most acceptable. It's also advisable for men to be clean shaven - stubble is generally frowned upon.
Women are also best off in a suit or at least a jacket.
Also as it's customary for shoes to be removed before entering certain buildings, rooms, restaurants etc, it's best to ensure that socks and tights are free from holes. Temperatures are usually between 0 and 10 degrees Celsius. February is the coldest month. The rainy season begins in mid to late June. Temperature and humidity is high.