July Weather in Cape Cod United States

Daily high temperatures increase by 2°F, from 76°F to 78°F, rarely falling below 68°F or exceeding 85°F. The highest daily average high temperature is 78°F on July 20.

Daily low temperatures increase by 3°F, from 62°F to 65°F, rarely falling below 56°F or exceeding 71°F. The highest daily average low temperature is 65°F on July 28.

For reference, on July 20, the hottest day of the year, temperatures in Cape Cod typically range from 65°F to 78°F, while on January 30, the coldest day of the year, they range from 26°F to 37°F.

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.

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The month of July in Cape Cod experiences essentially constant cloud cover, with the percentage of time that the sky is overcast or mostly cloudy remaining about 43% throughout the month.

The clearest day of the month is July 24, with clear, mostly clear, or partly cloudy conditions 58% of the time.

For reference, on May 23, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 55%, while on September 5, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 63%.

A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Cape Cod, the chance of a wet day over the course of July is increasing, starting the month at 25% and ending it at 31%.

For reference, the year's highest daily chance of a wet day is 33% on December 15, and its lowest chance is 24% on September 3.

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 Cape Cod is gradually increasing, starting the month at 2.6 inches, when it rarely exceeds 4.9 inches or falls below 1.0 inches, and ending the month at 2.9 inches, when it rarely exceeds 4.7 inches or falls below 1.4 inches.

The lowest average 31-day accumulation is 2.5 inches on July 7.

Over the course of July in Cape Cod, the length of the day is decreasing. From the start to the end of the month, the length of the day decreases by 44 minutes, implying an average daily decrease of 1 minute, 28 seconds, and weekly decrease of 10 minutes, 18 seconds.

The shortest day of the month is July 31, with 14 hours, 24 minutes of daylight and the longest day is July 1, with 15 hours, 9 minutes of daylight.

The earliest sunrise of the month in Cape Cod is 5:10 AM on July 1 and the latest sunrise is 24 minutes later at 5:34 AM on July 31.

The latest sunset is 8:19 PM on July 1 and the earliest sunset is 20 minutes earlier at 7:59 PM on July 31.

Daylight saving time is observed in Cape Cod during 2024, but it neither starts nor ends during July, so the entire month is in standard time.

For reference, on June 20, the longest day of the year, the Sun rises at 5:06 AM and sets 15 hours, 12 minutes later, at 8:18 PM, while on December 21, the shortest day of the year, it rises at 7:04 AM and sets 9 hours, 9 minutes later, at 4:13 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.

The figure below presents a compact representation of key lunar data for July 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.

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 Cape Cod is very rapidly increasing during July, rising from 20% to 41% over the course of the month.

For reference, on August 1, the muggiest day of the year, there are muggy conditions 41% of the time, while on December 12, the least muggy day of the year, there are muggy conditions 0% of the time.

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 Cape Cod is essentially constant during July, remaining within 0.2 miles per hour of 9.7 miles per hour throughout.

For reference, on January 13, the windiest day of the year, the daily average wind speed is 16.7 miles per hour, while on July 24, the calmest day of the year, the daily average wind speed is 9.5 miles per hour.

The lowest daily average wind speed during July is 9.5 miles per hour on July 24.

The hourly average wind direction in Cape Cod throughout July is predominantly from the south, with a peak proportion of 43% on July 27.

Cape Cod 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 Cape Cod is increasing during July, rising by 4°F, from 62°F to 66°F, over the course of the month.

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 Cape Cod typically lasts for 6.9 months (210 days), from around April 14 to around November 10, rarely starting before March 25 or after May 2, and rarely ending before October 21 or after November 29.

The month of July in Cape Cod 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 in Cape Cod are rapidly increasing during July, increasing by 598°F, from 649°F to 1,246°F, over the course of the month.

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 Cape Cod is gradually decreasing during July, falling by 0.7 kWh, from 7.0 kWh to 6.3 kWh, over the course of the month.

For the purposes of this report, the geographical coordinates of Cape Cod are 41.686 deg latitude, -70.243 deg longitude, and 0 ft elevation.

The topography within 2 miles of Cape Cod 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 Cape Cod is covered by artificial surfaces (53%) and trees (41%), within 10 miles by water (61%) and artificial surfaces (21%), and within 50 miles by water (80%) and trees (12%).