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Average Weather in July in Rio Dell California, United States

In Rio Dell, the month of July is characterized by gradually rising daily high temperatures, with daily highs increasing by 2°F, from 66°F to 68°F over the course of the month, and rarely exceeding 72°F or dropping below 62°F.

Daily low temperatures are around 51°F, rarely falling below 46°F or exceeding 55°F. The highest daily average low temperature is 52°F on July 27.

For reference, on August 22, the hottest day of the year, temperatures in Rio Dell typically range from 51°F to 68°F, while on December 23, the coldest day of the year, they range from 40°F to 53°F.

Average High and Low Temperature in July

The daily average high (red line) and low (blue line) temperature, with 25th to 75th and 10th to 90th percentile bands. The thin dotted lines are the corresponding average perceived temperatures.

The figure below shows you a compact characterization of the hourly average temperatures for the quarter of the year centered on July. 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.

Average Hourly Temperature in July

Average Hourly Temperature in July in Rio Dell18152229112233445566778899101011111212131314141515161617171818191920202121222223232424252526262727282829293030313112 AM4 AM8 AM12 PM4 PM8 PM12 AMJunAugcoldcoolcomfortablecoldcool
The average hourly temperature, color coded into bands: frigid < 15°F < freezing < 32°F < very cold < 45°F < cold < 55°F < cool < 65°F < comfortable < 75°F < warm < 85°F < hot < 95°F < sweltering. The shaded overlays indicate night and civil twilight.

Carahue, Chile (6,353 miles away) and Franklin, Australia (7,999 miles) are the far-away foreign places with temperatures most similar to Rio Dell (view comparison).

Clouds

The month of July in Rio Dell experiences decreasing cloud cover, with the percentage of time that the sky is overcast or mostly cloudy decreasing from 19% to 11%.

The clearest day of the month is July 28, with clear, mostly clear, or partly cloudy conditions 89% of the time.

For reference, on January 7, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 68%, while on August 3, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 90%.

Cloud Cover Categories in July

Cloud Cover Categories in July in Rio Dell1815222911223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303031310%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%JunAugJul 181%Jul 181%Jul 3189%Jul 3189%Jul 1185%Jul 1185%Jul 2188%Jul 2188%clearmostly clearovercastmostly cloudypartly cloudy
The percentage of time spent in each cloud cover band, categorized by the percentage of the sky covered by clouds: clear < 20% < mostly clear < 40% < partly cloudy < 60% < mostly cloudy < 80% < overcast.

Precipitation

A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Rio Dell, the chance of a wet day over the course of July is gradually decreasing, starting the month at 3% and ending it at 1%.

For reference, the year's highest daily chance of a wet day is 45% on December 4, and its lowest chance is 1% on July 29.

Probability of Precipitation in July

The percentage of days in which various types of precipitation are observed, excluding trace quantities: rain alone, snow alone, and mixed (both rain and snow fell in the same day).

Rainfall

To 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 July in Rio Dell is essentially constant, remaining about 0.2 inches throughout, and rarely exceeding 0.9 inches or falling below -0.0 inches.

The lowest average 31-day accumulation is 0.1 inches on July 30.

Average Monthly Rainfall in July

The average rainfall (solid line) accumulated over the course of a sliding 31-day period centered on the day in question, with 25th to 75th and 10th to 90th percentile bands. The thin dotted line is the corresponding average liquid-equivalent snowfall.

Sun

Over the course of July in Rio Dell, the length of the day is decreasing. From the start to the end of the month, the length of the day decreases by 42 minutes, implying an average daily decrease of 1 minute, 24 seconds, and weekly decrease of 9 minutes, 47 seconds.

The shortest day of the month is July 31, with 14 hours, 19 minutes of daylight and the longest day is July 1, with 15 hours, 1 minute of daylight.

Hours of Daylight and Twilight in July

The number of hours during which the Sun is visible (black line). From bottom (most yellow) to top (most gray), the color bands indicate: full daylight, twilight (civil, nautical, and astronomical), and full night.

The earliest sunrise of the month in Rio Dell is 5:49 AM on July 1 and the latest sunrise is 23 minutes later at 6:13 AM on July 31.

The latest sunset is 8:50 PM on July 1 and the earliest sunset is 19 minutes earlier at 8:31 PM on July 31.

Daylight saving time is observed in Rio Dell during 2017, but it neither starts nor ends during July, so the entire month is in daylight saving time.

For reference, on June 21, the longest day of the year, the Sun rises at 5:46 AM and sets 15 hours, 4 minutes later, at 8:50 PM, while on December 21, the shortest day of the year, it rises at 7:36 AM and sets 9 hours, 17 minutes later, at 4:53 PM.

Sunrise & Sunset with Twilight in July

The solar day over the course of July. From bottom to top, the black lines are the previous solar midnight, sunrise, solar noon, sunset, and the next solar midnight. The day, twilights (civil, nautical, and astronomical), and night are indicated by the color bands from yellow to gray.

Humidity

We 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 Rio Dell is essentially constant during July, remaining around 0% throughout.

Humidity Comfort Levels in July

The percentage of time spent at various humidity comfort levels, categorized by dew point: dry < 55°F < comfortable < 60°F < humid < 65°F < muggy < 70°F < oppressive < 75°F < miserable.

Wind

This 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 Rio Dell is decreasing during July, decreasing from 9.5 miles per hour to 8.3 miles per hour over the course of the month.

For reference, on June 22, the windiest day of the year, the daily average wind speed is 9.7 miles per hour, while on September 25, the calmest day of the year, the daily average wind speed is 7.5 miles per hour.

Average Wind Speed in July

The average of mean hourly wind speeds (dark gray line), with 25th to 75th and 10th to 90th percentile bands.
The hourly average wind direction in Rio Dell throughout July is predominantly from the north, with a peak proportion of 82% on July 1.

Wind Direction in July

Wind Direction in July in Rio Dell1815222911223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303031310%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%JunAugnorthwestsouth
The percentage of hours in which the mean wind direction is from each of the four cardinal wind directions (north, east, south, and west), excluding hours in which the mean wind speed is less than 1 mph. The lightly tinted areas at the boundaries are the percentage of hours spent in the implied intermediate directions (northeast, southeast, southwest, and northwest).

Water Temperature

Rio Dell 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 Rio Dell is essentially constant during July, remaining around 53°F throughout.

Average Water Temperature in July

The daily average water temperature (purple line), with 25th to 75th and 10th to 90th percentile bands.

Growing Season

Definitions 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 Rio Dell typically lasts for 9.4 months (282 days), from around February 23 to around December 2, rarely starting after April 5, or ending before November 6.

The month of July in Rio Dell is reliably fully within the growing season.

Time Spent in Various Temperature Bands and the Growing Season in July

Time Spent in Various Temperature Bands and the Growing Season in July in Rio Dellgrowing seasongrowing season1815222911223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303031310%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%JunAug100%Jul 16100%Jul 16Jul 24100%Jul 24100%coldcoolcomfortablevery cold
The percentage of time spent in various temperature bands: frigid < 15°F < freezing < 32°F < very cold < 45°F < cold < 55°F < cool < 65°F < comfortable < 75°F < warm < 85°F < hot < 95°F < sweltering. The black line is the percentage chance that a given day is 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 in Rio Dell are increasing during July, increasing by 258°F, from 572°F to 829°F, over the course of the month.

Growing Degree Days in July

The average growing degree days accumulated over the course of July, with 25th to 75th and 10th to 90th percentile bands.

Solar Energy

This 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 Rio Dell is essentially constant during July, remaining within 0.2 kWh of 8.0 kWh throughout.

Average Daily Incident Shortwave Solar Energy in July

The average daily shortwave solar energy reaching the ground per square meter (orange line), with 25th to 75th and 10th to 90th percentile bands.

Topography

For the purposes of this report, the geographical coordinates of Rio Dell are 40.499 deg latitude, -124.106 deg longitude, and 417 ft elevation.

The topography within 2 miles of Rio Dell contains very significant variations in elevation, with a maximum elevation change of 1,394 feet and an average elevation above sea level of 422 feet. Within 10 miles contains very significant variations in elevation (3,524 feet). Within 50 miles also contains extreme variations in elevation (6,234 feet).

The area within 2 miles of Rio Dell is covered by trees (66%) and artificial surfaces (13%), within 10 miles by trees (65%) and shrubs (14%), and within 50 miles by water (45%) and trees (36%).

Data Sources

This report illustrates the typical weather in Rio Dell year round, 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 are 3 weather stations near enough to contribute to our estimation of the temperature and dew point in Rio Dell.

For each station, the records are corrected for the elevation difference between that station and Rio Dell 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 Rio Dell is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Rio Dell and a given station.

The stations contributing to this reconstruction are: Arcata-Eureka Airport (68%, 53 kilometers, north); Lonnie Pool Field Weaverville Airport (20%, 104 kilometers, east); and Ukiah Municipal Airport (12%, 171 kilometers, southeast).

Other Data

All data relating to the Sun's position (e.g., sunrise and sunset) are computed using astronomical formulas from the book, Astronomical Tables of the Sun, Moon and Planets , 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 aiports and weather stations are provided by AskGeo.com .

Maps are © Esri, with data from National Geographic, Esri, DeLorme, NAVTEQ, UNEP-WCMC, USGS, NASA, ESA, METI, NRCAN, GEBCO, NOAA, and iPC.

Disclaimer

The 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.