September Weather in Novato California, United States
Daily high temperatures decrease by 2°F, from 81°F to 79°F, rarely falling below 69°F or exceeding 91°F.
Daily low temperatures decrease by 2°F, from 52°F to 50°F, rarely falling below 45°F or exceeding 56°F.
For reference, on August 24, the hottest day of the year, temperatures in Novato typically range from 52°F to 81°F, while on December 31, the coldest day of the year, they range from 39°F to 55°F.
Average High and Low Temperature in September in Novato
The figure below shows you a compact characterization of the hourly average temperatures for the quarter of the year centered on September. 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 September in Novato
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 month of September in Novato experiences gradually increasing cloud cover, with the percentage of time that the sky is overcast or mostly cloudy increasing from 11% to 18%.
The clearest day of the month is September 1, with clear, mostly clear, or partly cloudy conditions 89% of the time.
For reference, on January 11, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 56%, while on July 20, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 92%.
Cloud Cover Categories in September in Novato
0% clear 20% mostly clear 40% partly cloudy 60% mostly cloudy 80% overcast 100%
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Novato, the chance of a wet day over the course of September is gradually increasing, starting the month at 1% and ending it at 5%.
For reference, the year's highest daily chance of a wet day is 32% on February 20, and its lowest chance is 0% on July 28.
Probability of Precipitation in September in Novato
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 September in Novato is gradually increasing, starting the month at 0.1 inches, when it rarely exceeds 0.2 inches or falls below -0.0 inches, and ending the month at 0.5 inches, when it rarely exceeds 1.3 inches.
Average Monthly Rainfall in September in Novato
Over the course of September in Novato, the length of the day is rapidly decreasing. From the start to the end of the month, the length of the day decreases by 1 hour, 10 minutes, implying an average daily decrease of 2 minutes, 25 seconds, and weekly decrease of 16 minutes, 56 seconds.
The shortest day of the month is September 30, with 11 hours, 50 minutes of daylight and the longest day is September 1, with 13 hours, 0 minutes of daylight.
Hours of Daylight and Twilight in September in Novato
The earliest sunrise of the month in Novato is 6:39 AM on September 1 and the latest sunrise is 25 minutes later at 7:05 AM on September 30.
The latest sunset is 7:39 PM on September 1 and the earliest sunset is 45 minutes earlier at 6:54 PM on September 30.
Daylight saving time is observed in Novato during 2023, but it neither starts nor ends during September, so the entire month is in daylight saving time.
For reference, on June 21, the longest day of the year, the Sun rises at 5:47 AM and sets 14 hours, 49 minutes later, at 8:36 PM, while on December 22, the shortest day of the year, it rises at 7:23 AM and sets 9 hours, 31 minutes later, at 4:54 PM.
Sunrise & Sunset with Twilight in September in Novato
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.
Solar Elevation and Azimuth in September in Novato
The figure below presents a compact representation of key lunar data for September 2023. 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.
Moon Rise, Set & Phases in September in Novato
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 Novato is essentially constant during September, remaining around 0% throughout.
For reference, on July 5, the muggiest day of the year, there are muggy conditions 0% of the time, while on January 18, the least muggy day of the year, there are muggy conditions 0% of the time.
Humidity Comfort Levels in September in Novato
dry 55°F comfortable 60°F humid 65°F muggy 70°F oppressive 75°F miserable
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 Novato is essentially constant during September, remaining within 0.2 miles per hour of 7.2 miles per hour throughout.
For reference, on May 30, the windiest day of the year, the daily average wind speed is 8.7 miles per hour, while on October 21, the calmest day of the year, the daily average wind speed is 6.8 miles per hour.
Average Wind Speed in September in Novato
The hourly average wind direction in Novato throughout September is predominantly from the west, with a peak proportion of 86% on September 1.
Wind Direction in September in Novato
Novato 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 Novato is essentially constant during September, remaining around 57°F throughout.
The highest average surface water temperature during September is 57°F on September 20.
Average Water Temperature in September in Novato
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 Novato typically lasts for 10 months (312 days), from around January 30 to around December 8, rarely starting after February 28, or ending before November 16.
The month of September in Novato is reliably fully within the growing season.
Time Spent in Various Temperature Bands and the Growing Season in September in Novato
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
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 Novato are increasing during September, increasing by 360°F, from 1,953°F to 2,313°F, over the course of the month.
Growing Degree Days in September in Novato
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 Novato is rapidly decreasing during September, falling by 1.5 kWh, from 6.8 kWh to 5.3 kWh, over the course of the month.
Average Daily Incident Shortwave Solar Energy in September in Novato
For the purposes of this report, the geographical coordinates of Novato are 38.107 deg latitude, -122.570 deg longitude, and 26 ft elevation.
The topography within 2 miles of Novato contains significant variations in elevation, with a maximum elevation change of 568 feet and an average elevation above sea level of 91 feet. Within 10 miles contains significant variations in elevation (1,880 feet). Within 50 miles contains very significant variations in elevation (4,698 feet).
The area within 2 miles of Novato is covered by artificial surfaces (43%), cropland (27%), and herbaceous vegetation (22%), within 10 miles by grassland (40%) and trees (15%), and within 50 miles by water (38%) and grassland (19%).
This report illustrates the typical weather in Novato, 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 2 weather stations near enough to contribute to our estimation of the temperature and dew point in Novato.
For each station, the records are corrected for the elevation difference between that station and Novato 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 Novato is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Novato 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 Novato 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.
All 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.
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.
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