At sea level on the north coast, monthly average maximum temperatures range between 85-90 degree F and minimum between 68-74 degrees F. There are two wet seasons, May-June and September-October; the least rain falls in February and March. The seasons are quite variable, however, and may not follow this pattern.
During December, January and February, the "Christmas Winds" blow throughout the Caribbean. These are strong ENE winds, usually over 20 knots, and are especially prevalent in the afternoons. The prevailing trade winds bring rain from the northeast, and the north shores are well-watered, with a number of rivers. Parts of the south coast are in the rain shadow.
In general, the island is most lush and green at the northeast end, progressively becoming drier until a desert-like environment is established from Montego Bay west to Negril. It is more like a savannah on a coastal plain. A mist forest can be found on Blue Mountain. Closer to the laboratory is Fern Valley, a moist area with huge ferns blotting out the sun.