Fall Weather in Walden United StatesDaily high temperatures decrease by 30°F, from 82°F to 53°F, rarely falling below 41°F or exceeding 89°F. Daily low temperatures decrease by 28°F, from 63°F to 35°F, rarely falling below 23°F or exceeding 69°F. For reference, on July 21, the hottest day of the year, temperatures in Walden typically range from 67°F to 85°F, while on January 23, the coldest day of the year, they range from 29°F to 46°F. The figure below shows you a compact characterization of the hourly average fall 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. Massanzago-Ca' Baglioni-San Dono, Italy (4,857 miles away) is the far-away foreign place with temperatures most similar to Walden (view comparison). CloudsThe fall in Walden experiences rapidly increasing cloud cover, with the percentage of time that the sky is overcast or mostly cloudy increasing from 35% to 49%. The lowest chance of overcast or mostly cloudy conditions is 33% on September 19. The clearest day of the fall is September 19, with clear, mostly clear, or partly cloudy conditions 67% of the time. For reference, on January 3, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 56%, while on September 19, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 67%. PrecipitationA wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Walden, the chance of a wet day over the course of the fall is essentially constant, remaining around 26% throughout. For reference, the year's highest daily chance of a wet day is 44% on July 8, and its lowest chance is 21% on October 15. Over the course of the fall in Walden, the chance of a day with only rain remains an essentially constant 25% throughout, the chance of a day with mixed snow and rain remains an essentially constant 1% throughout, and the chance of a day with only snow remains an essentially constant 0% throughout. 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 fall in Walden is rapidly increasing, starting the season at 3.0 inches, when it rarely exceeds 5.6 inches or falls below 1.1 inches, and ending the season at 4.9 inches, when it rarely exceeds 8.4 inches or falls below 2.1 inches. The highest average 31-day accumulation is 4.9 inches on November 30. SunOver the course of the fall in Walden, the length of the day is very rapidly decreasing. From the start to the end of the season, the length of the day decreases by 2 hours, 55 minutes, implying an average daily decrease of 1 minute, 56 seconds, and weekly decrease of 13 minutes, 35 seconds. The shortest day of the fall is November 30, with 9 hours, 58 minutes of daylight and the longest day is September 1, with 12 hours, 53 minutes of daylight. The latest sunrise of the fall in Walden is 8:03 AM on November 2 and the earliest sunrise is 59 minutes earlier at 7:04 AM on November 3. The latest sunset is 8:07 PM on September 1 and the earliest sunset is 2 hours, 38 minutes earlier at 5:29 PM on November 30. Daylight saving time (DST) starts at 1:00 AM on November 3, 2024, shifting sunrise and sunset to be an hour later. For reference, on June 20, the longest day of the year, the Sun rises at 6:27 AM and sets 14 hours, 32 minutes later, at 8:58 PM, while on December 21, the shortest day of the year, it rises at 7:46 AM and sets 9 hours, 47 minutes later, at 5:33 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 fall 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 Walden is very rapidly decreasing during the fall, falling from 55% to 0% over the course of the season. For reference, on July 23, the muggiest day of the year, there are muggy conditions 82% of the time, while on December 17, 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 Walden is increasing during the fall, increasing from 3.4 miles per hour to 4.9 miles per hour over the course of the season. For reference, on February 26, the windiest day of the year, the daily average wind speed is 5.7 miles per hour, while on July 31, the calmest day of the year, the daily average wind speed is 3.2 miles per hour. The hourly average wind direction in Walden throughout the fall is predominantly from the south, with a peak proportion of 41% on November 28. 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). The growing season in Walden typically lasts for 6.6 months (204 days), from around April 6 to around October 27, rarely starting before March 15 or after April 25, and rarely ending before October 8 or after November 14. During the fall in Walden, the chance that a given day is within the growing season is very rapidly decreasing falling from 100% to -0% over the course of the season. 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 Walden are rapidly increasing during the fall, increasing by 889°F, from 3,114°F to 4,003°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 Walden is very rapidly decreasing during the fall, falling by 3.2 kWh, from 5.8 kWh to 2.6 kWh, over the course of the season. TopographyFor the purposes of this report, the geographical coordinates of Walden are 35.165 deg latitude, -85.301 deg longitude, and 1,900 ft elevation. The topography within 2 miles of Walden contains very significant variations in elevation, with a maximum elevation change of 1,365 feet and an average elevation above sea level of 1,493 feet. Within 10 miles also contains very significant variations in elevation (1,824 feet). Within 50 miles contains very significant variations in elevation (3,720 feet). The area within 2 miles of Walden is covered by trees (97%), within 10 miles by trees (71%) and artificial surfaces (18%), and within 50 miles by trees (67%) and cropland (27%). Data SourcesThis report illustrates the typical weather in Walden, based on a statistical analysis of historical hourly weather reports and model reconstructions from January 1, 1980 to December 31, 2016. Temperature and Dew PointThere are 4 weather stations near enough to contribute to our estimation of the temperature and dew point in Walden. For each station, the records are corrected for the elevation difference between that station and Walden according to the International Standard Atmosphere , and by the relative change present in the MERRA-2 satellite-era reanalysis between the two locations. The estimated value at Walden is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Walden and a given station. The stations contributing to this reconstruction are:
To get a sense of how much these sources agree with each other, you can view a comparison of Walden and the stations that contribute to our estimates of its temperature history and climate. Please note that each source's contribution is adjusted for elevation and the relative change present in the MERRA-2 data. Other DataAll data relating to the Sun's position (e.g., sunrise and sunset) are computed using astronomical formulas from the book, Astronomical Algorithms 2nd Edition , by Jean Meeus. All other weather data, including cloud cover, precipitation, wind speed and direction, and solar flux, come from NASA's MERRA-2 Modern-Era Retrospective Analysis . This reanalysis combines a variety of wide-area measurements in a state-of-the-art global meteorological model to reconstruct the hourly history of weather throughout the world on a 50-kilometer grid. Land Use data comes from the Global Land Cover SHARE database , published by the Food and Agriculture Organization of the United Nations. Elevation data comes from the Shuttle Radar Topography Mission (SRTM) , published by NASA's Jet Propulsion Laboratory. Names, locations, and time zones of places and some airports come from the GeoNames Geographical Database . Time zones for airports and weather stations are provided by AskGeo.com . Maps are © OpenStreetMap contributors. 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. We further caution that our travel scores are only as good as the data that underpin them, that weather conditions at any given location and time are unpredictable and variable, and that the definition of the scores reflects a particular set of preferences that may not agree with those of any particular reader. Please review our full terms contained on our Terms of Service page. |