Sometimes the weather is nice even in this season, it does not rain all the time.
To enjoy traveling around Osaka in this season, how about going to ONSEN nearby?! Onsen is, as you know, hot spring, which is nice to relieve your tired body during your trip.
The best hot spring resort around Osaka is Arima Onsen in Kobe-city, Hyogo.
It is just an hour and 1,330yen oneway from Umeda (Osaka) station
to the middle of Arima onsen by Hankyu bus.
as there are some one-day hot spring places
for about 600 - 1,000yen for taking a bath,
and about 3,000 - 7,000yen with lunch.
My recommendation is GOSHOBO
with retro and modern flavor.
Also you will enjoy the nature and the old small
town with nice restaurants, souvenir shops there.
> Take a look of Arima onsen one day trip by one of Our staff Jun.
In Osaka-city, there are also some Onsen spots.
One is SPA WORLD in the middle of city center, where you can enjoy many kinds of hot spring.
They offer 1,000yen campaign oftern... or almost always.
Another is NOBUTA NO YU, which is about 30min from the hostel by subway.
There are chartered bath rooms with a small sitting space for a family for about 4,000yen/hour.
We are happy to help your ONSEN experience here!
Arima Onsen : http://www.arima-onsen.com/index.html
Hankyu Bus : http://bus.hankyu.co.jp/highway/highway10.html
Goshobo : http://www.goshobo.co.jp/goshobo/
Spa World : http://www.spaworld.co.jp/
Nobuta no yu : http://www.nobuta123.co.jp/nobehatsuruhashi/family/index.html