If you are from Canada, you will barely notice the difference. For Dominicans, February weather is cold! Dominicans leave the beaches to the foreigners in winter (January-February), when temperatures during the day may drop to a "chilly" 25 degrees Celsius.
For insights into weather year round in the DR, see these two pages, one in the Travel section of DR1 and the other in the Living section (this one on the light side.)
http://dr1.com/living/settling/2.shtml (on the light side)
http://dr1.com/travel/expect/weather.shtml (answering frequently asked questions about weather)