Clouds

In New York City on October 9, the average percentage of the sky covered by clouds does not show significant systematic variation over the course of the day, with the percentage of time that the sky is overcast or mostly cloudy remaining about 37% throughout the day. For reference, on January 3, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 53%, while on August 28, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 64%. Cloud Cover Categories on October 9 Cloud Cover Categories on October 9 in New York City night day night 12 AM 3 AM 6 AM 9 AM 12 PM 3 PM 6 PM 9 PM 12 AM 0% 100% 10% 90% 20% 80% 30% 70% 40% 60% 50% 50% 60% 40% 70% 30% 80% 20% 90% 10% 100% 0% 2:30 AM 61% 2:30 AM 61% 7:30 PM 64% 7:30 PM 64% clear mostly clear partly cloudy mostly cloudy overcast 0% clear 20% mostly clear 40% partly cloudy 60% mostly cloudy 80% overcast 100% The percentage of time spent in each cloud cover band, categorized by the percentage of the sky covered by clouds. Civil twilight and night are indicated by shaded overlays.

Precipitation

On average, there is a 25% chance that more than 0.04 inches of total precipitation will fall in New York City throughout the day on October 9, all of which can be expected to be rain. For reference, the year's highest daily chance of precipitation is 35% on July 31, and its lowest chance is 22% on January 28. For those 25% of years with precipitation on October 9, the chart below shows when throughout the day that precipitation is more or less likely to occur, excluding hourly accumulations of less than 0.01 inches. If precipitation were equally likely throughout the day, all hours would report 4.2% (100% divided by 24 hours). Precipitation is most likely between 3 AM and 4 AM, and least likely between 10 AM and 11 AM. Hourly Share of Precipitation on October 9 Hourly Share of Precipitation on October 9 in New York City night day night 12 AM 3 AM 6 AM 9 AM 12 PM 3 PM 6 PM 9 PM 12 AM 0.0% 0.5% 1.0% 1.5% 2.0% 2.5% 3.0% 3.5% 4.0% 4.5% 5.0% 4.2% 4.2% 3 AM 4.8% 3 AM 4.8% 10 AM 3.7% 10 AM 3.7% rain The share of the day's precipitation attributable to each hour of the day, excluding trace quantities, and color-coded as rain alone, snow alone, and mixed (both rain and snow fell during the same hour). Civil twilight and night are indicated by shaded overlays.

Sun

In New York City on Friday, October 9, 2020, the Sun rises at 7:01 AM and sets 11 hours, 23 minutes later, at 6:24 PM. Solar noon is at 12:42 PM. For reference, on June 20, the longest day of the year, the Sun rises at 5:24 AM and sets 15 hours, 6 minutes later, at 8:30 PM, while on December 21, the shortest day of the year, it rises at 7:16 AM and sets 9 hours, 15 minutes later, at 4:32 PM. Civil twilight, the period before the Sun has risen or after the Sun has set during which time it is possible to engage in most outdoor activities without artificial lighting, begins and ends 27 minutes before sunrise and after sunset, at 6:33 AM and 6:51 PM respectively. Nautical twilight, during which time it is possible to clearly discern the horizon (e.g., for navigational purposes), begins and ends 59 minutes before sunrise and after sunset, at 6:02 AM and 7:23 PM respectively. Astronomical twilight, outside of which it is possible to make the most sensitive of astronomical observations, begins and ends 1 hour, 31 minutes before sunrise and after sunset, at 5:30 AM and 7:54 PM respectively. Solar Elevation on October 9, 2020 Solar Elevation on October 9, 2020 in New York City night day night 12 AM 3 AM 6 AM 9 AM 12 PM 3 PM 6 PM 9 PM 12 AM -80 deg -60 deg -40 deg -20 deg 0 deg 20 deg 40 deg 60 deg 80 deg solar noon 12:42 PM solar noon 12:42 PM 7:01 AM rise 7:01 AM rise 6:24 PM set 6:24 PM set summer solstice summer solstice winter solstice winter solstice Elevation of the center of the Sun above (positive) or below (negative) the horizon (black line). Yellow and gray fills indicate day and night, respectively. Light gray lines are the corresponding curves for the winter and summer solstices. Civil twilight and night are indicated by shaded overlays.

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. In New York City on October 9, the chance of muggy conditions does not change significantly over the course of the day, remaining around 6% throughout. Humidity Comfort Levels on October 9 Humidity Comfort Levels on October 9 in New York City night day night 12 AM 3 AM 6 AM 9 AM 12 PM 3 PM 6 PM 9 PM 12 AM 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 6:30 AM 5% 6:30 AM 5% 5:30 PM 6% 5:30 PM 6% humid comfortable dry muggy dry 55°F comfortable 60°F humid 65°F muggy 70°F oppressive 75°F miserable The percentage of time spent at various humidity comfort levels, categorized by dew point. Civil twilight and night are indicated by shaded overlays.

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 New York City on October 9 varies throughout the day, with a daily average of 8.1 miles per hour. The windiest time of day is around 2:45 PM, with an average hourly wind speed of 8.8 miles per hour, mostly staying between 5.9 miles per hour and 11.4 miles per hour, and rarely falling below 3.6 miles per hour or exceeding 14.4 miles per hour. The calmest time of day is around 6:45 AM, with an average hourly wind speed of 7.7 miles per hour, mostly staying between 5.9 miles per hour and 9.1 miles per hour, and rarely falling below 4.3 miles per hour or exceeding 11.6 miles per hour. For reference, on February 26, the windiest day of the year, the daily average wind speed is 10.3 miles per hour, while on July 31, the calmest day of the year, the daily average wind speed is 6.2 miles per hour. Wind Speed on October 9 Wind Speed on October 9 in New York City night day night 12 AM 3 AM 6 AM 9 AM 12 PM 3 PM 6 PM 9 PM 12 AM 0 mph 2 mph 4 mph 6 mph 8 mph 10 mph 12 mph 14 mph 2:45 PM 8.8 mph 2:45 PM 8.8 mph 7.7 mph 6:45 AM 7.7 mph 6:45 AM The average of mean hourly wind speeds (dark gray line), with 25th to 75th and 10th to 90th percentile bands. Civil twilight and night are indicated by shaded overlays. Over the entire course of October 9 in New York City, the hourly average wind direction, in order of prevalence, is from the west (32%), north (27%), south (26%), and east (15%). Wind Direction on October 9 Wind Direction on October 9 in New York City night day night 12 AM 3 AM 6 AM 9 AM 12 PM 3 PM 6 PM 9 PM 12 AM 0% 100% 20% 80% 40% 60% 60% 40% 80% 20% 100% 0% west south north east northeastsouthwest The percentage of hours in which the mean wind direction is from each of the four cardinal wind directions, excluding hours in which the mean wind speed is less than 1.0 mph. The lightly tinted areas at the boundaries are the percentage of hours spent in the implied intermediate directions (northeast, southeast, southwest, and northwest). Civil twilight and night are indicated by shaded overlays.

Water Temperature

New York City 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 does not change appreciably over the course of the day, so this section does not include a chart. The average surface water temperature on October 9 in New York City is 65°F, mostly staying between 63°F and 66°F, and rarely falling below 62°F or exceeding 67°F. For reference, the year's highest average is 73°F on August 10, and its lowest average is 39°F on February 23.

Shortwave Solar Power

This section discusses the incident shortwave solar power 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 peak incident shortwave solar power per square meter is 0.58 kilowatts at around 12:45 PM. In contrast, the corresponding value on June 29, the brightest day of the year, is 0.81 kilowatts at around 11:45 AM. The corresponding value on December 22, the darkest day of the year, is 0.32 kilowatts at around 11:00 AM. Shortwave Solar Power on October 9 Shortwave Solar Power on October 9 in New York City night day night 12 AM 3 AM 6 AM 9 AM 12 PM 3 PM 6 PM 9 PM 12 AM 0.0 kW 0.5 kW 1.0 kW 1.5 kW 2.0 kW 12:45 PM 0.58 kW 12:45 PM 0.58 kW Dec 22 Dec 22 Average incident shortwave solar power reaching the ground per square meter (orange line), with 25th to 75th and 10th to 90th percentile bands. Light gray lines are the corresponding curves for the days with the minimum and maximum average total solar energy reaching the ground. Civil twilight and night are indicated by shaded overlays.

Topography

For the purposes of this report, the geographical coordinates of New York City are 40.714 deg latitude, -74.006 deg longitude, and 30 ft elevation. The topography within 2 miles of New York City is essentially flat, with a maximum elevation change of 85 feet and an average elevation above sea level of 11 feet. Within 10 miles is essentially flat (367 feet). Within 50 miles contains only modest variations in elevation (1,657 feet). The area within 2 miles of New York City is covered by water (58%) and artificial surfaces (40%), within 10 miles by artificial surfaces (78%) and water (20%), and within 50 miles by artificial surfaces (32%) and trees (32%).

Data Sources