This report describes the typical weather at the Cayenne-Rochambeau Airport (Cayenne, French Guiana) weather station over the course of an average May. It is based on the historical records from 1992 to 2012. Earlier records are either unavailable or unreliable.
Cayenne has a tropical monsoon climate with short dry season. The area within 25 mi of this station is covered by forests (67%) and oceans and seas (31%).
The month of May is characterized by essentially constant daily high temperatures, with daily highs around 85°F throughout the month, exceeding 88°F or dropping below 82°F only one day in ten.
Over the course of May, the length of the day is essentially constant. The shortest day of the month is May 2 with 12:18 hours of daylight; the longest day is May 29 with 12:23 hours of daylight.
The earliest sunrise is at 6:15am on May 23; the latest sunset is at 6:39pm on May 31; the latest sunrise is at 6:18am on May 1; the earliest sunset is at 6:35pm on May 6.
Daylight saving time (DST) is not observed in 2012.
The median cloud cover ranges from 71% (partly cloudy) to 76% (partly cloudy). The trend is for the sky to be clearing with the median cloud cover decreasing by 5% from the start to the end of the month.
On May 16, a representative day, the sky is clear or mostly clear 10% of the time, partly cloudy 37% of the time, and mostly cloudy or overcast 44% of the time.
The probability that precipitation will be observed at this location varies throughout the month. Precipitation is most likely around May 30, occurring in 84% of days. Precipitation is least likely around May 1, occurring in 80% of days.
Throughout May, the most common forms of precipitation are moderate rain, light rain, and thunderstorms.
Moderate rain is the most severe precipitation observed during 62% of those days with precipitation. It is most likely around May 23, when it is observed during 51% of all days.
Light rain is the most severe precipitation observed during 18% of those days with precipitation. It is most likely around May 3, when it is observed during 16% of all days.
Thunderstorms are the most severe precipitation observed during 12% of those days with precipitation. They are most likely around May 30, when it is observed during 12% of all days.
Either snow is exceptionally unlikely to fall at this location in May or this station does not reliably report precipitation types.
The relative humidity typically ranges from 69% (mildly humid) to 99% (very humid) over the course of a typical May, rarely dropping below 60% (mildly humid) and reaching as high as 100% (very humid).
The air is driest around May 31, at which time the relative humidity drops below 75% (humid) three days out of four; it is most humid around May 29, rising above 100% (very humid) three days out of four.
Dew point is often a better measure of how comfortable a person will find the weather than relative humidity because it more directly relates to whether perspiration will evaporate from the skin, thereby cooling the body. Lower dew points feel drier and higher dew points feel more humid.
Over the course of a typical May, the dew point typically varies from 72°F (very muggy) to 77°F (oppressive) and is rarely below 71°F (very muggy) or above 79°F (oppressive).
Over the course of May typical wind speeds vary from 0 mph to 14 mph (calm to moderate breeze), rarely exceeding 18 mph (fresh breeze).
The highest average wind speed of 6 mph (light breeze) occurs around May 1, at which time the average daily maximum wind speed is 14 mph (moderate breeze).
The lowest average wind speed of 4 mph (light breeze) occurs around May 31, at which time the average daily maximum wind speed is 13 mph (moderate breeze).