Summer Weather in Terceira Island PortugalDaily high temperatures increase by 8°F, from 69°F to 77°F, rarely falling below 65°F or exceeding 82°F. The highest daily average high temperature is 78°F on August 12. Daily low temperatures increase by 7°F, from 60°F to 67°F, rarely falling below 55°F or exceeding 72°F. The highest daily average low temperature is 67°F on August 12. For reference, on August 11, the hottest day of the year, temperatures in Terceira Island typically range from 67°F to 78°F, while on February 13, the coldest day of the year, they range from 54°F to 62°F. The figure below shows you a compact characterization of the hourly average summer temperatures. The horizontal axis is the day, the vertical axis is the hour of the day, and the color is the average temperature for that hour and day. CloudsThe summer in Terceira Island experiences decreasing cloud cover, with the percentage of time that the sky is overcast or mostly cloudy decreasing from 50% to 39%. The lowest chance of overcast or mostly cloudy conditions is 25% on July 17. The clearest day of the summer is July 17, with clear, mostly clear, or partly cloudy conditions 75% of the time. For reference, on December 15, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 63%, while on July 17, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 75%. PrecipitationA wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Terceira Island, the chance of a wet day over the course of the summer is essentially constant, remaining around 11% throughout. For reference, the year's highest daily chance of a wet day is 36% on December 7, and its lowest chance is 5% on July 10. RainfallTo show variation within the season and not just the monthly totals, we show the rainfall accumulated over a sliding 31-day period centered around each day. The average sliding 31-day rainfall during the summer in Terceira Island is essentially constant, remaining about 0.7 inches throughout, and rarely exceeding 2.4 inches. The lowest average 31-day accumulation is 0.3 inches on July 20. SunOver the course of the summer in Terceira Island, the length of the day is rapidly decreasing. From the start to the end of the season, the length of the day decreases by 1 hour, 40 minutes, implying an average daily decrease of 1 minute, 6 seconds, and weekly decrease of 7 minutes, 41 seconds. The shortest day of the summer is August 31, with 13 hours, 2 minutes of daylight and the longest day is June 20, with 14 hours, 53 minutes of daylight. The earliest sunrise of the summer in Terceira Island is 6:23 AM on June 13 and the latest sunrise is 54 minutes later at 7:17 AM on August 31. The latest sunset is 9:17 PM on June 28 and the earliest sunset is 58 minutes earlier at 8:19 PM on August 31. Daylight saving time is observed in Terceira Island during 2024, but it neither starts nor ends during the summer, so the entire season is in standard time. For reference, on June 20, the longest day of the year, the Sun rises at 6:24 AM and sets 14 hours, 53 minutes later, at 9:16 PM, while on December 21, the shortest day of the year, it rises at 8:03 AM and sets 9 hours, 27 minutes later, at 5:30 PM. The figure below presents a compact representation of the sun's elevation (the angle of the sun above the horizon) and azimuth (its compass bearing) for every hour of every day in the reporting period. The horizontal axis is the day of the year and the vertical axis is the hour of the day. For a given day and hour of that day, the background color indicates the azimuth of the sun at that moment. The black isolines are contours of constant solar elevation. MoonThe figure below presents a compact representation of key lunar data for the summer of 2024. The horizontal axis is the day, the vertical axis is the hour of the day, and the colored areas indicate when the moon is above the horizon. The vertical gray bars (new Moons) and blue bars (full Moons) indicate key Moon phases. The label associated with each bar indicates the date and time that the phase is obtained, and the companion time labels indicate the rise and set times of the Moon for the nearest time interval in which the moon is above the horizon. HumidityWe base the humidity comfort level on the dew point, as it determines whether perspiration will evaporate from the skin, thereby cooling the body. Lower dew points feel drier and higher dew points feel more humid. Unlike temperature, which typically varies significantly between night and day, dew point tends to change more slowly, so while the temperature may drop at night, a muggy day is typically followed by a muggy night. The chance that a given day will be muggy in Terceira Island is very rapidly increasing during the summer, rising from 4% to 47% over the course of the season. The highest chance of a muggy day during the summer is 51% on August 12. For reference, on August 12, the muggiest day of the year, there are muggy conditions 51% of the time, while on March 3, the least muggy day of the year, there are muggy conditions 0% of the time. WindThis section discusses the wide-area hourly average wind vector (speed and direction) at 10 meters above the ground. The wind experienced at any given location is highly dependent on local topography and other factors, and instantaneous wind speed and direction vary more widely than hourly averages. The average hourly wind speed in Terceira Island is decreasing during the summer, decreasing from 12.7 miles per hour to 11.6 miles per hour over the course of the season. For reference, on December 26, the windiest day of the year, the daily average wind speed is 18.7 miles per hour, while on July 16, the calmest day of the year, the daily average wind speed is 10.0 miles per hour. The lowest daily average wind speed during the summer is 10.0 miles per hour on July 17. The wind direction in Terceira Island during the summer is predominantly out of the west from June 1 to June 19 and from July 16 to August 31 and the north from June 19 to July 16. Water TemperatureTerceira Island is located near a large body of water (e.g., ocean, sea, or large lake). This section reports on the wide-area average surface temperature of that water. The average surface water temperature in Terceira Island is rapidly increasing during the summer, rising by 9°F, from 64°F to 73°F, over the course of the season. The highest average surface water temperature during the summer is 73°F on August 24. Growing SeasonDefinitions of the growing season vary throughout the world, but for the purposes of this report, we define it as the longest continuous period of non-freezing temperatures (≥ 32°F) in the year (the calendar year in the Northern Hemisphere, or from July 1 until June 30 in the Southern Hemisphere). Temperatures in Terceira Island 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. Growing degree days are a measure of yearly heat accumulation used to predict plant and animal development, and defined as the integral of warmth above a base temperature, discarding any excess above a maximum temperature. In this report, we use a base of 50°F and a cap of 86°F. The average accumulated growing degree days in Terceira Island are very rapidly increasing during the summer, increasing by 1,802°F, from 1,426°F to 3,227°F, over the course of the season. Solar EnergyThis section discusses the total daily incident shortwave solar energy reaching the surface of the ground over a wide area, taking full account of seasonal variations in the length of the day, the elevation of the Sun above the horizon, and absorption by clouds and other atmospheric constituents. Shortwave radiation includes visible light and ultraviolet radiation. The average daily incident shortwave solar energy in Terceira Island is decreasing during the summer, falling by 1.2 kWh, from 7.0 kWh to 5.8 kWh, over the course of the season. The highest average daily incident shortwave solar energy during the summer is 7.4 kWh on July 16. TopographyFor the purposes of this report, the geographical coordinates of Terceira Island are 38.717 deg latitude, -27.217 deg longitude, and 0 ft elevation. The topography within 2 miles of Terceira Island is essentially flat, with a maximum elevation change of 0 feet and an average elevation above sea level of 0 feet. Within 10 miles is also essentially flat (0 feet). Within 50 miles is also essentially flat (0 feet). The area within 2 miles of Terceira Island is covered by grassland (100%), within 10 miles by water (55%) and grassland (32%), and within 50 miles by water (98%). Data SourcesThis report illustrates the typical weather in Terceira Island, based on a statistical analysis of historical hourly weather reports and model reconstructions from January 1, 1980 to December 31, 2016. The details of the data sources used for this report can be found on the Lajes Field page. DisclaimerThe information on this site is provided as is, without any assurances as to its accuracy or suitability for any purpose. Weather data is prone to errors, outages, and other defects. We assume no responsibility for any decisions made on the basis of the content presented on this site. We draw particular cautious attention to our reliance on the MERRA-2 model-based reconstructions for a number of important data series. While having the tremendous advantages of temporal and spatial completeness, these reconstructions: (1) are based on computer models that may have model-based errors, (2) are coarsely sampled on a 50 km grid and are therefore unable to reconstruct the local variations of many microclimates, and (3) have particular difficulty with the weather in some coastal areas, especially small islands. 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