Jamaica Temperature And Climate History
As in the other Caribbean islands the monthly temperature range in Jamaica is small. Thus by analyzing the climate in Ocho Rios Jamaica, the difference between the hottest month, July (81.4°F.) and the coolest, January (75.8°F.) is less than 6°F. The range between day and night is somewhat greater (15°F. to 20°F.); though owing to the moderating influence of the sea it is rare for day temperatures on the plains to exceed 91° F. or to fall below 60°F at night. Highland temperatures are 10°F to 20°F lower than these, and the summits of the Blue Mountains have been known to have occasional light frosts in winter. The climate and weather in Jamaica has been relatively the same for several decades. Unfortunately many scientists have not been able to truly document what is the water temperature in Jamaica.
Rainfall In Jamaica
The chief features of rainfall in Jamaica have been examined by the meteorological service located on the Port Royal highway. In Jamaica the rainy season begins at about the end of April and reaches a maximum in September, October and November with a somewhat drier intervening period in June. Several factors combine to produce the summer maximum. First, as the convection currents are strongest in the hot months, the heaviest showers occur then.
This is the basic nature of Jamaica climate. Thunder often accompanies afternoon downpours. Second, this is the period when the Inter- Tropical Convergence Zone is farthest north and rain-bearing easterly waves, moving along its northern boundary, sometimes cross the island. Third, this is the hurricane season. Though hurricanes strike Jamaica on an average only once in seven or eight years, they bring such heavy rain when they strike or pass nearby that average monthly rainfall figures are affected.
In the colder months convection currents are weaker and the air is less humid, so showers are fewer, lighter and shorter. The tendency to drought is partly offset by occasional northern winds blowing out from North America in winter. When a northern reaches Jamaica, the weather on the northern side of the island changes dramatically. Along the north coast, temperature drops by several degrees, winds are strong, and skies are grey, rain falls, and tourism suffers. This is key when assessing current weather in Jamaica.
Further inland, on north-facing slopes, the rain may be very heavy indeed. But the southern plains are cast in rain shadow, and though the weather is cool the skies may be cloudless. As you can see from Map 5f, these areas are also in rain shadow when the winds are blowing from the east or north-east. As a result, rainfall is low and the dry season is long. Streams flowing down the southern slopes of the Blue Mountains are reduced to mere trickles most of the time and sometimes they dry up altogether. Several parts of the largest and driest lowlands are irrigated. For example, near Spanish Town the whole flow of the Rio Cobre River is diverted into irrigation channels where the water is used mainly for the cultivation of sugar cane. These matters have implications on what are the normal weather patterns of Jamaica.