I had a look at the long-term weather expectations (I did before on previous Eurocades, and they tend to be surprisingly accurate) and it looks really really great:
Friday (set-up day) : sunny, 20 degrees
Saturday: mostly sunny, 19 degrees
Sunday (clean-up day): occasional showers, 19 degrees
http://www.accuweather.com/nl/nl/rotterdam/251688/september-weather/251688So....not too hot, not too cold and mostly dry

An advice for everyone: If you want to enjoy the full "Eurocade experience" I would strongly suggest to arrive on the friday.
First drop-off your machine(s) at the clubhouse so the Eurocade crew has plenty of time to set it up and you can go to the Hotel and check in, maybe have a refreshing nab and shower after the long travel and then get your ass back to the clubhouse to enjoy the set-up....

Usually we are done around dinner time so the friday evening leaves plenty of time for a cosy pre-party

Then the saturday will be a relaxed day of play and fun from 10 am till around midnight.
Sunday is "clean up day", we have to remove all the cabs and bring back the clubhouse in original condition.
This would require a two-night stay for you guys, from friday to sunday.
YOU CAN STILL GET A ROOM FOR 2 NIGHTS FOR 2 PERSONS FOR THE VERY CHEAP PRICE OF €115 TOTAL INCL. AN EXCELLENT BREAKFAST AT THE VAN DER VALK HOTEL WHICH IS VERY CLOSE TO THE VENUE:
https://bookingtool.valk.com/Hotel%20Ridderkerk/en/0/?_ga=1.65742318.152343622.1341414125
Even if you're not 100% sure at this moment I highly suggest reserving a room NOW because you can still cancel it FREE until 24h. of your stay. Prices may well go up or the Hotel may even be booked full when you wait with reserving !!Also, please inform us of your plans, cab, day of arrival/leave so we can schedule everything.