One of the top questions we get asked is: what’s the Belize annual rainfall? Generally, Belize enjoys good sub-tropical weather. The Belize Weather Report and 24 hour Forecast on our home page will give you an idea of current weather. The following summary of Belize Annual Rainfall and other weather data is courtesy of the Belize Weather Bureau:
Belize is situated on the Caribbean coast of Central America with Mexico to the North and Guatemala to the west and south. It lies between 15º45´ and 18º30´N and 87º30´ and 89º15´W. The terrain is low and flat along coastal areas and in some northern regions of the country while in the central and southern regions low mountains rise gradually to a height of 3,685 feet.
The country’s weather is characterized by two seasons: a rainy and a dry season. Belize annual rainfall: most of the year’s rainfall occurs during the period June to November, that is, the rainy season. It is noted that the transition from dry to the rainy is very sharp. Annual rainfall ranges from 60 inches (1524mm) in the north to 160 inches (4064mm) in the south. Except for the southern regions, the rainfall is variable from year to year.
The onset of the rainy season begins in the early May in Toledo, (where the annual rainfall is highest) progressing north to the Stann Creek, Belize, Cayo and Orange Walk District in late May, followed by Corozal District in early June. The mean temperature varies from 81°F/ 27°C along the coast to 69°F/21°C in the hills. The coldest month is January while the highest temperatures are experienced during the month of May.
Inland stations tend to have more extreme temperatures than coastal stations where the sea breeze moderates the temperature. For example average maximum and minimum temperatures at Central Farm are both hotter and colder than those of the Philip Goldson International Airport.
Annual Temperatures By Location
Average Annual temperatures at Central Farm (Cayo), Philip Goldson Int’l Airport (Belize District) and Cooma Cairn (Belize Mountains):
Belize Inland Central Farm Cayo District: Average Maximum 88.3°F 31.3°C Average Minimum 68.9°F 20.5°C
Belize Coast Phillip Goldson International Airport:: Average Maximum 86.2°F 30.1°C Average Minimum 72.6°F 22.6°C
Belize Mountains Cooma Cairn: Average Maximum 77.5°F 25.3°C Average Minimum 63.8°F 17.7°C
Philip Goldson International Airport has an elevation of 4 meters above sea level and is located 5 miles from the coast; El Cayo is about 50 miles inland with an approximate elevation of about 150 metres above sea level; Cooma Cairn is located in the Mountain Pine Ridge Area and is about 952 meters above sea level. The difference between the average temperatures between the coast and the mountains is about 8.8°F/4.8°C indicating a decrease of temperature with height.
Rainfall By Region
In the south the rainfall is further enhanced by the intrusion of the Inter- Tropical Convergence Zone (ITCZ) as it journeys northwards. Orographic lifting over steep slopes in the south also enhances rainfall activity. The southern region has one maximum which occurs in the month of July and is by far the wettest month.
Central Regions show a primary and secondary maxima occurring in June and September. Each of these is significantly less than the single maximum for the south.
The data for the Northern region show that rainfall is more evenly distributed during the same period with no significant variation as in the other regions.
The rainy season exhibits a break or mark decrease in the month of August. This break is known as the “Mauga” season. However, this pattern is not evident in the Toledo district.
The main synoptic features that influence Belize annual rainfall trends are Tropical waves, Tropical storms and Hurricanes which move westward through the Caribbean from June to November. Tropical waves can be active or inactive systems and peak activity occurs during the months of June and July. Tropical storms and hurricanes peak during the months of September and October even though they vary in number from year to year.
In addition there are cold fronts that progress southeastward from the Continental USA into the Northwest Caribbean. The effect of frontal activity on rainfall distribution and therefore climatic conditions begins in October and ends in April peaking through December and January. A cold front moves across the country about once every 10 days.
Upper level troughs show no preferential time of occurrence. Although cold fronts affect the country from October through to April the most likely months for frontal passages are December, January and February (Figure 4). In December and January fronts are most likely to become stationary over Belize. Surface troughs show a modal frequency in November with secondary maxima in December. Cold core lows frequently occur in the months of July, August and September. Those not of the cold core variety are found most frequently in July and August.
Other features include upper level troughs and cold core lows to lesser degrees; these sometimes interact with surface low level troughs resulting in the enhancement of precipitation.
The transition from wet to dry is a gradual process. The dry season is from November to May with April as the driest month. The dry season can be subdivided into a cool transition from November to February, as a result of the incursion of frontal systems and a warm dry period from March to May when high pressure systems in the Atlantic produce stable and windy south easterlies.
Normally the rainy season in Belize starts during the last week of May and the first week in June over southern Belize, and the second to third week of June over northern regions of the country. Occasionally, the onset of the rains is seen over the entire country during late May or during the first and second week of June when a significant tropical system makes its entry into the NW Caribbean and northern Central America. Additionally, there could be false starts of the rainy season in late May and early June, and the real onset of the rains is not seen until mid or late June.
During intense drought conditions over the NW Caribbean region, the rains are not seen in June or even July and the onset of the rainy season is delayed until late August or September as were the case in 1974 and 1975, which were significant dry years.
One criterion for the onset of the rainy season is two consecutive days of rainfall accumulation of 30 mm or more, and four of the following seven days are rain days of 1 mm rainfall accumulation or more.
Ramon Frutos – Consulting Meteorologist
Reference: Belize Weather Bureau, Leyton Research, Hydrology Unit