Turning On Snow In The City
Go into the chat window and enter "Let it snow" and then post it. That will make it start to snow! Once you've had enough snow, you can stop it by going back into the chat window and type in "No more snow". The down side to this cheat is that it will only work when it's really winter, so you will have to wait to enter it.
Turning The Rain Off And On
When you are playing in Global or Alliance chat, you can type in the phrase "A storm is brewing" and then post it. Next, you'll need to exit the chat screen and when you do, it will be raining in your city. If you want to stop the rain, simply type and post the phrase "No more rain". *Please note: This code is seasonal only and doesn't work all the time.