We were in April and there was no snow. the monkeys barely entered the hot springs. They were out of the water. for us, it would be better to go to that area when there is snow. without it loses charm. In my opinion.

I went there by car based on Google Maps or GPS Navigator in my car. You have to pay 500 円 for car parking. From parking lot, you have to climb up mountain for approximately 600 meters, but it feels a lot. Park entrance fee is 800 円 for adults. Discounts for group visitors and children are applicable. It is not really worth it for a single adult visitor. Better to visit with many children as then per head cost will come down significantly. There are the same monkeys wandering even outside the park and you need not even enter the park.

There is a charge for parking on the Shibu Onsen side.

Yes, in the lower entrance as well as in the upper entrance. Of course, clean and nice !

It lasts about 4 months, from December to the end of March

Just visited and heaps of monkeys. No hot pools though as damaged during recent typhoon, no update when will be fixed. You can see monkeys all year round, April is awesome timing.

It will snow from December.

Wild monkeys enter the hot spring only during the winter snow season. The field monkey park is covered with snow, and people go to the park, so if the shoe bottom is jagged, it is slippery, but you can walk. You can check it because there is a live camera for the park hot spring and the place where the wild monkey is in. Pre-checking is essential because you can see the hourly crowded condition. The appearance comes down from the mountain several times a day because there is a feeding time

The 30 min walk is on a snow-covered path with ice on parts. If need be, there is a shop at the entrance before the path where you can get some 'claws' to wear onto the bottom of your shoes so that you can walk safely. If kids are very young, it's advisable to carry them with child or baby harness. At the park itself, follow the guidelines on how to treat the snow monkeys.

Probably won't be snow then.