Average Weather in União Brazil
In União, the wet season is hot and overcast, the dry season is sweltering and partly cloudy, and it is oppressive year round. Over the course of the year, the temperature typically varies from 73°F to 99°F and is rarely below 69°F or above 103°F.
Based on the beach/pool score, the best time of year to visit União for hot-weather activities is from late June to late August.
The hot season lasts for 3.0 months, from September 3 to December 2, with an average daily high temperature above 97°F. The hottest day of the year is October 9, with an average high of 99°F and low of 76°F.
The cool season lasts for 5.7 months, from January 19 to July 10, with an average daily high temperature below 92°F. The coldest day of the year is July 26, with an average low of 73°F and high of 93°F.
Average High and Low Temperature
The figure below shows you a compact characterization of the entire year of hourly average temperatures. The horizontal axis is the day of the year, the vertical axis is the hour of the day, and the color is the average temperature for that hour and day.
Average Hourly Temperature
In União, the average percentage of the sky covered by clouds experiences extreme seasonal variation over the course of the year.
The clearer part of the year in União begins around May 31 and lasts for 4.6 months, ending around October 20. On July 25, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 69% of the time, and overcast or mostly cloudy 31% of the time.
The cloudier part of the year begins around October 20 and lasts for 7.4 months, ending around May 31. On April 8, the cloudiest day of the year, the sky is overcast or mostly cloudy 85% of the time, and clear, mostly clear, or partly cloudy 15% of the time.
Cloud Cover Categories
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in União varies very significantly throughout the year.
The wetter season lasts 4.6 months, from December 28 to May 15, with a greater than 42% chance of a given day being a wet day. The chance of a wet day peaks at 82% on March 22.
The drier season lasts 7.4 months, from May 15 to December 28. The smallest chance of a wet day is 2% on August 12.
Among wet days, we distinguish between those that experience rain alone, snow alone, or a mixture of the two. Based on this categorization, the most common form of precipitation throughout the year is rain alone, with a peak probability of 82% on March 22.
Daily Chance of Precipitation
To show variation within the months and not just the monthly totals, we show the rainfall accumulated over a sliding 31-day period centered around each day of the year. União experiences extreme seasonal variation in monthly rainfall.
The rainy period of the year lasts for 8.7 months, from October 13 to July 3, with a sliding 31-day rainfall of at least 0.5 inches. The most rain falls during the 31 days centered around March 28, with an average total accumulation of 11.0 inches.
The rainless period of the year lasts for 3.3 months, from July 3 to October 13. The least rain falls around August 7, with an average total accumulation of 0.2 inches.
Average Monthly Rainfall
The length of the day in União does not vary substantially over the course of the year, staying within 23 minutes of 12 hours throughout. In 2018, the shortest day is June 21, with 11 hours, 51 minutes of daylight; the longest day is December 21, with 12 hours, 23 minutes of daylight.
Hours of Daylight and Twilight
The earliest sunrise is at 5:26 AM on November 10, and the latest sunrise is 35 minutes later at 6:01 AM on July 20. The earliest sunset is at 5:42 PM on October 24, and the latest sunset is 31 minutes later at 6:14 PM on February 2.
Daylight saving time (DST) is not observed in União during 2018.
Sunrise & Sunset with Twilight
União experiences some seasonal variation in the perceived humidity.
The muggier period of the year lasts for 9.2 months, from October 24 to July 30, during which time the comfort level is muggy, oppressive, or miserable at least 84% of the time. The muggiest day of the year is April 5, with muggy conditions 100% of the time.
The least muggy day of the year is August 30, with muggy conditions 78% of the time.
Humidity Comfort Levels
The average hourly wind speed in União experiences mild seasonal variation over the course of the year.
The windier part of the year lasts for 5.4 months, from July 13 to December 25, with average wind speeds of more than 3.1 miles per hour. The windiest day of the year is October 20, with an average hourly wind speed of 4.0 miles per hour.
The calmer time of year lasts for 6.6 months, from December 25 to July 13. The calmest day of the year is April 18, with an average hourly wind speed of 2.3 miles per hour.
Average Wind Speed
The predominant average hourly wind direction in União varies throughout the year.
The wind is most often from the east for 8.5 months, from April 7 to December 23, with a peak percentage of 67% on June 21. The wind is most often from the north for 3.5 months, from December 23 to April 7, with a peak percentage of 49% on January 1.
Best Time of Year to Visit
To characterize how pleasant the weather is in União throughout the year, we compute two travel scores.
The tourism score favors clear, rainless days with perceived temperatures between 65°F and 80°F. Based on this score, the best time of year to visit União for general outdoor tourist activities is from late June to late August, with a peak score in the last week of July.
The beach/pool score favors clear, rainless days with perceived temperatures between 75°F and 90°F. Based on this score, the best time of year to visit União for hot-weather activities is from late June to late August, with a peak score in the last week of July.
For each hour between 8:00 AM and 9:00 PM of each day in the analysis period (1980 to 2016), independent scores are computed for perceived temperature, cloud cover, and total precipitation. Those scores are combined into a single hourly composite score, which is then aggregated into days, averaged over all the years in the analysis period, and smoothed.
Our cloud cover score is 10 for fully clear skies, falling linearly to 9 for mostly clear skies, and to 1 for fully overcast skies.
Our precipitation score, which is based on the three-hour precipitation centered on the hour in question, is 10 for no precipitation, falling linearly to 9 for trace precipitation, and to 0 for 0.04 inches of precipitation or more.
Our tourism temperature score is 0 for perceived temperatures below 50°F, rising linearly to 9 for 65°F, to 10 for 75°F, falling linearly to 9 for 80°F, and to 1 for 90°F or hotter.
Our beach/pool temperature score is 0 for perceived temperatures below 65°F, rising linearly to 9 for 75°F, to 10 for 82°F, falling linearly to 9 for 90°F, and to 1 for 100°F or hotter.
Temperatures in União are sufficiently warm year round that it is not entirely meaningful to discuss the growing season in these terms. We nevertheless include the chart below as an illustration of the distribution of temperatures experienced throughout the year.
Time Spent in Various Temperature Bands and the Growing Season
Growing Degree Days
The average daily incident shortwave solar energy experiences some seasonal variation over the course of the year.
The brighter period of the year lasts for 3.0 months, from August 21 to November 20, with an average daily incident shortwave energy per square meter above 6.6 kWh. The brightest day of the year is September 30, with an average of 7.1 kWh.
The darker period of the year lasts for 2.3 months, from March 8 to May 18, with an average daily incident shortwave energy per square meter below 5.1 kWh. The darkest day of the year is April 18, with an average of 4.6 kWh.
Average Daily Incident Shortwave Solar Energy
For the purposes of this report, the geographical coordinates of União are -4.586 deg latitude, -42.864 deg longitude, and 177 ft elevation.
The topography within 2 miles of União contains only modest variations in elevation, with a maximum elevation change of 335 feet and an average elevation above sea level of 178 feet. Within 10 miles also contains only modest variations in elevation (466 feet). Within 50 miles contains only modest variations in elevation (1,050 feet).
The area within 2 miles of União is covered by trees (26%), shrubs (24%), grassland (23%), and cropland (11%), within 10 miles by trees (54%) and shrubs (24%), and within 50 miles by trees (58%) and shrubs (21%).
This report illustrates the typical weather in União, based on a statistical analysis of historical hourly weather reports and model reconstructions from January 1, 1980 to December 31, 2016.
Temperature and Dew Point
There is only a single weather station, Teresina Airport, in our network suitable to be used as a proxy for the historical temperature and dew point records of União.
At a distance of 53 kilometers from União, closer than our threshold of 150 kilometers, this station is deemed sufficiently nearby to be relied upon as our primary source for temperature and dew point records.
The station records are corrected for the elevation difference between the station and União according to the International Standard Atmosphere , and by the relative change present in the MERRA-2 satellite-era reanalysis between the two locations.
Please note that the station records themselves may additionally have been back-filled using other nearby stations or the MERRA-2 reanalysis.
Time zones for aiports and weather stations are provided by AskGeo.com .