What you are looking for is the yeast's attenuation. Attenuation is basically the ammount of sugar the yeast is able to convert in the wort. This is different for each yeast strain and is listed on the company's website. Here is what White Labs has on the subject.
You're FG is dependent on the level of attenuation the yeast can provide along with how many fermentable sugars you have. Temperature does play a part, but it is usually when you ferment too cold. They yeast will stop working at lower temperatures. I've seen most people recommend 64F - 70F for fermenting ales with most ale yeast strains.
If you tell us what yeast you used, the OG, along with a rough outline of the recipe (e.g. 6 lbs liquid extra + 1lb or 2lb of steeping graings), then some people will be able to tell you if there is anything for you to worry about.