May Weather at Arcata-Eureka Airport California, United StatesDaily high temperatures increase by 2°F, from 58°F to 61°F, rarely falling below 54°F or exceeding 65°F. Daily low temperatures increase by 4°F, from 45°F to 49°F, rarely falling below 38°F or exceeding 54°F. For reference, on September 10, the hottest day of the year, temperatures at Arcata-Eureka Airport typically range from 50°F to 65°F, while on December 22, the coldest day of the year, they range from 41°F to 54°F. The figure below shows you a compact characterization of the hourly average temperatures for the quarter of the year centered on May. 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. Ancud, Chile (6,536 miles away) and Cygnet, Tasmania, Australia (8,018 miles) are the far-away foreign places with temperatures most similar to Arcata-Eureka Airport (view comparison). CloudsThe month of May at Arcata-Eureka Airport experiences decreasing cloud cover, with the percentage of time that the sky is overcast or mostly cloudy decreasing from 52% to 41%. The clearest day of the month is May 31, with clear, mostly clear, or partly cloudy conditions 59% of the time. For reference, on January 9, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 68%, while on August 2, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 89%. PrecipitationA wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. At Arcata-Eureka Airport, the chance of a wet day over the course of May is very rapidly decreasing, starting the month at 21% and ending it at 12%. For reference, the year's highest daily chance of a wet day is 47% on December 3, and its lowest chance is 1% on August 2. RainfallTo show variation within the month and not just the monthly total, we show the rainfall accumulated over a sliding 31-day period centered around each day. The average sliding 31-day rainfall during May at Arcata-Eureka Airport is rapidly decreasing, starting the month at 2.1 inches, when it rarely exceeds 4.2 inches or falls below 0.4 inches, and ending the month at 1.0 inches, when it rarely exceeds 3.1 inches. SunOver the course of May at Arcata-Eureka Airport, the length of the day is increasing. From the start to the end of the month, the length of the day increases by 55 minutes, implying an average daily increase of 1 minute, 50 seconds, and weekly increase of 12 minutes, 51 seconds. The shortest day of the month is May 1, with 14 hours, 0 minutes of daylight and the longest day is May 31, with 14 hours, 55 minutes of daylight. The latest sunrise of the month at Arcata-Eureka Airport is 6:13 AM on May 1 and the earliest sunrise is 27 minutes earlier at 5:46 AM on May 31. The earliest sunset is 8:13 PM on May 1 and the latest sunset is 28 minutes later at 8:42 PM on May 31. Daylight saving time is observed at Arcata-Eureka Airport during 2024, but it neither starts nor ends during May, so the entire month is in daylight saving time. For reference, on June 20, the longest day of the year, the Sun rises at 5:44 AM and sets 15 hours, 8 minutes later, at 8:51 PM, while on December 21, the shortest day of the year, it rises at 7:38 AM and sets 9 hours, 14 minutes later, at 4:51 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 May 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 at Arcata-Eureka Airport is essentially constant during May, remaining around 0% throughout. For reference, on May 12, the muggiest day of the year, there are muggy conditions 0% of the time, while on January 1, 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 at Arcata-Eureka Airport is essentially constant during May, remaining within 0.2 miles per hour of 8.4 miles per hour throughout. For reference, on December 12, the windiest day of the year, the daily average wind speed is 9.2 miles per hour, while on September 24, the calmest day of the year, the daily average wind speed is 6.9 miles per hour. The hourly average wind direction at Arcata-Eureka Airport throughout May is predominantly from the north, with a peak proportion of 67% on May 31. Water TemperatureArcata-Eureka Airport 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 at Arcata-Eureka Airport is essentially constant during May, remaining around 52°F throughout. 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 at Arcata-Eureka Airport typically lasts for 9.3 months (282 days), from around February 28 to around December 6, rarely starting after April 3, or ending before November 8. The month of May at Arcata-Eureka Airport is reliably fully within the growing 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 at Arcata-Eureka Airport are gradually increasing during May, increasing by 117°F, from 240°F to 357°F, over the course of the month. 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 at Arcata-Eureka Airport is increasing during May, rising by 1.1 kWh, from 6.2 kWh to 7.2 kWh, over the course of the month. TopographyFor the purposes of this report, the geographical coordinates of Arcata-Eureka Airport are 40.972 deg latitude, -124.107 deg longitude, and 200 ft elevation. The topography within 2 miles of Arcata-Eureka Airport contains significant variations in elevation, with a maximum elevation change of 495 feet and an average elevation above sea level of 142 feet. Within 10 miles contains significant variations in elevation (2,877 feet). Within 50 miles contains large variations in elevation (7,503 feet). The area within 2 miles of Arcata-Eureka Airport is covered by trees (30%), herbaceous vegetation (23%), water (23%), and cropland (11%), within 10 miles by trees (44%) and water (40%), and within 50 miles by water (44%) and trees (41%). Data SourcesThis report illustrates the typical weather at Arcata-Eureka Airport, based on a statistical analysis of historical hourly weather reports and model reconstructions from January 1, 1980 to December 31, 2016. Temperature and Dew PointArcata-Eureka Airport has a weather station that reported reliably enough during the analysis period that we have included it in our network. When available, historical temperature and dew point measurements are taken directly from this weather station. These records are obtained from NOAA's Integrated Surface Hourly data set, falling back on ICAO METAR records as required. In the case of missing or erroneous measurements from this station, we fall back on records from nearby stations, adjusted according to typical seasonal and diurnal intra-station differences. For a given day of the year and hour of the day, the fallback station is selected to minimize the prediction error over the years for which there are measurements for both stations. The stations on which we may fall back are Jack Mc Namara Field, Redding Municipal Airport, and Red Bluff Municipal Airport. 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. 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