It is always a good idea to have savings tucked away for a rainy day. Emergencies such as legal or medical bills or loss of a job can all force you into 'rainy day' mode. Planning can make these types of events easier to handle. Determine how big your rainy day savings need to be by factoring in emergency spending needs and essential spending needs if your source of income is interrupted. Once you know what you will need, put together a plan based on your current savings, monthly savings and the number of months you want to take to build your rainy day fund.