This report describes the typical weather at the Rio de Janeiro-Galeão International Airport (Rio de Janeiro, Brazil) weather station over the course of an average year. It is based on the historical records from 1974 to 2012. Earlier records are either unavailable or unreliable.
Rio de Janeiro has a tropical savanna climate with dry winters. The area within 25 mi of this station is covered by croplands (33%), oceans and seas (27%), built-up areas (23%), forests (11%), and grasslands (7%).
Over the course of a year, the temperature typically varies from 63°F to 92°F and is rarely below 58°F or above 100°F.
The warm season lasts from January 5 to March 17 with an average daily high temperature above 89°F. The hottest day of the year is February 19, with an average high of 92°F and low of 75°F.
The cold season lasts from May 15 to October 7 with an average daily high temperature below 82°F. The coldest day of the year is July 16, with an average low of 63°F and high of 79°F.
The length of the day varies significantly over the course of the year. The shortest day is June 20 with 10:44 hours of daylight; the longest day is December 21 with 13:33 hours of daylight.
The earliest sunrise is at 5:16am on October 20 and the latest sunset is at 7:44pm on January 15. The latest sunrise is at 6:47am on February 24 and the earliest sunset is at 5:15pm on June 4.
Daylight savings time (DST) is observed in this location during 2012, starting in the spring on October 21 and ending in the fall on February 25.
The median cloud cover ranges from 65% (partly cloudy) to 88% (mostly cloudy). The sky is cloudiest on October 12 and clearest on June 17. The clearer part of the year begins around January 26. The cloudier part of the year begins around August 26.
On June 17, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 42% of the time, and overcast or mostly cloudy 29% of the time.
On October 12, the cloudiest day of the year, the sky is overcast, mostly cloudy, or partly cloudy 64% of the time, and clear or mostly clear 17% of the time.
The probability that precipitation will be observed at this location varies throughout the year. Precipitation is most likely around January 1, occurring in 57% of days. Precipitation is least likely around July 10, occurring in 25% of days.
Over the entire year, the most common forms of precipitation are light rain, thunderstorms, moderate rain, and drizzle.
Light rain is the most severe precipitation observed during 32% of those days with precipitation. It is most likely around October 22, when it is observed during 20% of all days.
Thunderstorms are the most severe precipitation observed during 32% of those days with precipitation. They are most likely around January 19, when it is observed during 31% of all days.
Moderate rain is the most severe precipitation observed during 22% of those days with precipitation. It is most likely around December 3, when it is observed during 12% of all days.
Drizzle is the most severe precipitation observed during 13% of those days with precipitation. It is most likely around October 3, when it is observed during 9% of all days.
During the warm season, which lasts from January 5 to March 17, there is a 50% average chance that precipitation will be observed at some point during a given day. When precipitation does occur it is most often in the form of thunderstorms (55% of days with precipitation have at worst thunderstorms), light rain (21%), moderate rain (17%), and drizzle (6%).
During the cold season, which lasts from May 15 to October 7, there is a 32% average chance that precipitation will be observed at some point during a given day. When precipitation does occur it is most often in the form of light rain (41% of days with precipitation have at worst light rain), moderate rain (25%), drizzle (21%), and thunderstorms (12%).
Either snow is exceptionally unlikely to fall at any time during the year at this location or this station does not reliably report precipitation types.
The relative humidity typically ranges from 53% (mildly humid) to 98% (very humid) over the course of the year, rarely dropping below 32% (comfortable) and reaching as high as 100% (very humid).
The air is driest around August 17, at which time the relative humidity drops below 63% (mildly humid) three days out of four; it is most humid around May 2, exceeding 95% (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 year, the dew point typically varies from 58°F (comfortable) to 75°F (very muggy) and is rarely below 51°F (very comfortable) or above 80°F (very oppressive).
Over the course of the year typical wind speeds vary from 0 mph to 15 mph (calm to moderate breeze), rarely exceeding 21 mph (fresh breeze).
The highest average wind speed of 33 mph (high wind) occurs around October 29, at which time the average daily maximum wind speed is 15 mph (moderate breeze).
The lowest average wind speed of 4 mph (light breeze) occurs around June 22, at which time the average daily maximum wind speed is 10 mph (gentle breeze).