2013 could be the best year for comets since 1996-1997 when Hyakutake, and Hale-Bopp made their appearances. Two potentially naked eye comets are being tracked. One may be visible in March and the other in December.
Disclaimer: Predictions like this are always made with apprehension. Sometimes they fail to meet brightness predictions, and sometimes they don’t look as expected. There are four types of comets: those that fail to match predictions, those that unexpectedly perform, those that perform as expected, and those that perform as expected but are hard to see anyway.
There are two types of bright comets: those that pass near the sun, and those that pass near the Earth. Bright comets that give off lots of dust and gas near perihelion are at their best in either the morning or evening as they approach, or recede from, the sun. These may easily visible for days or a couple weeks. They may have great tails. But they have to be extremely bright to be visible near the sun. Some extremely bright comets have only been visible by satellite. <note: link may be intermittent??>