Not sure if this has been posted before.

On March 14, 2015, the NEX Tokyo Direct Ticket will be discontinued and replaced by the NEX Tokyo Round Trip Ticket. The new ticket will provide a round trip from the airport into Tokyo/Yokohama and back to the airport within a 14 day period. Unfortunately, the cost will increase to 4000 yen, effectively reducing the discount over regular tickets to "only" 33-55 percent. A one way option will not be available.

http://www.japan-guide.com/e/e2359_nex.html

You can check the weather information here http://www.jnto.go.jp/weather/eng/index.php