Fermentation done in three days?

I made my first batch, a Little Kings cream ale from AHS, on Saturday and I noticed today that fermentation had stopped. I had missed the target OG of 1.048 by quite a bit, and hit 1.030. It has also been cold here and the temps in the house have gotten down into the high 50's a couple of times. I was worried, so I took a hydrometer sample and the SG is at the recipe target FG of 1.012.

The sample tastes a little rough, but good in a hoppy way. I plan on leaving the beer in the fermenter for another couple of weeks and then bottling, but should I expect any further fermentation out of this batch?

Probably not. The yeast is done eating sugar and will finish its job in the next few weeks cleaning up your beer.

If your OG was 1.030 and you're at 1.012 now, its probably not stopped. It may appear so, but there's no way to observe fermentation stopping other than getting the same reading on your hydro three days in a row.

But...I bet you its stopped, and for a different reason. It is very difficult to miss your OG on an extract brew. There's no points to be lost other than possible a couple from the steeping grains, but certainly not 18 points, unless you topped up to 8 gallons.

Many first time extract brewers thing they missed it, but if you were at the right volume, got all the extract in there...then you were most likely around 1.048. Its also very hard to thoroughly mix your top up water with the wert...and that is the cause of often low readings of extract brewers.

1.012 would be right where one would expect a 1.048 brew to finish. A 1.030 brew, properly pitched and fermented would go to about 1.007.

I believe it is mostly done. I don't understand why people think fermentation has to take more than week. It's harder to believe in this case because the temperature is very low. I once did a brew in record time. I opened a bottle about 10 days after brewing. Yes that is true. It didn't taste very good but did get better after a month.

IMHO from reading a lot on this board, most people that are fans of 3,4, 5 week primaries do not think that fermentation necessarily takes longer than a week. They, along with me, believe that 2-4 weeks in primary after fermentation is done will clear the beer, mellow/meld the flavors, and create a very tight and compact yeast cake to rack off.

I agree with VTBrewer. Probably didn't mix it well enough to get the proper OG reading. I have made every mistake you can brewing extract and never could miss the gravity by more than a few points.