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Average Weather in August in Tripoli Iowa, United States

Daily high temperatures decrease by 3°F, from 82°F to 78°F, rarely falling below 69°F or exceeding 89°F.

Daily low temperatures decrease by 5°F, from 63°F to 59°F, rarely falling below 48°F or exceeding 72°F.

For reference, on July 17, the hottest day of the year, temperatures in Tripoli typically range from 64°F to 83°F, while on January 22, the coldest day of the year, they range from 12°F to 27°F.

Average High and Low Temperature in August

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 August. 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 August

Average Hourly Temperature in August in Tripoli18152229112233445566778899101011111212131314141515161617171818191920202121222223232424252526262727282829293030313112 AM4 AM8 AM12 PM4 PM8 PM12 AMJulSepNowNowcoldcoolcoolcomfortablecomfortablewarmcold
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 average hourly temperature, color coded into bands. The shaded overlays indicate night and civil twilight.

Almaty, Kazakhstan (6,460 miles away) is the far-away foreign place with temperatures most similar to Tripoli (view comparison).


The month of August in Tripoli experiences essentially constant cloud cover, with the percentage of time that the sky is overcast or mostly cloudy remaining about 31% throughout the month.

The clearest day of the month is August 5, with clear, mostly clear, or partly cloudy conditions 70% of the time.

For reference, on February 6, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 58%, while on July 27, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 70%.

Cloud Cover Categories in August

Cloud Cover Categories in August in Tripoli1815222911223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303031310%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%JulSepAug 169%Aug 169%Aug 3168%Aug 3168%Aug 1169%Aug 1169%Aug 2169%Aug 2169%NowNowclearmostly clearpartly cloudymostly cloudyovercast
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.


A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Tripoli, the chance of a wet day over the course of August is gradually decreasing, starting the month at 37% and ending it at 34%.

For reference, the year's highest daily chance of a wet day is 43% on June 9, and its lowest chance is 11% on January 22.

Probability of Precipitation in August

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).


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 August in Tripoli is essentially constant, remaining about 3.8 inches throughout, and rarely exceeding 6.9 inches or falling below 1.7 inches.

Average Monthly Rainfall in August

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.


Over the course of August in Tripoli, 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, 17 minutes, implying an average daily decrease of 2 minutes, 34 seconds, and weekly decrease of 17 minutes, 57 seconds.

The shortest day of the month is August 31, with 13 hours, 11 minutes of daylight and the longest day is August 1, with 14 hours, 28 minutes of daylight.

Hours of Daylight and Twilight in August

Hours of Daylight and Twilight in August in Tripoli1815222911223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303031310 hr24 hr4 hr20 hr8 hr16 hr12 hr12 hr16 hr8 hr20 hr4 hr24 hr0 hrJulSepnightnightdaydayAug 114 hr, 28 minAug 114 hr, 28 minAug 3113 hr, 11 minAug 3113 hr, 11 minNowNow
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 Tripoli is 6:00 AM on August 1 and the latest sunrise is 32 minutes later at 6:33 AM on August 31.

The latest sunset is 8:28 PM on August 1 and the earliest sunset is 45 minutes earlier at 7:44 PM on August 31.

Daylight saving time is observed in Tripoli during 2020, but it neither starts nor ends during August, so the entire month is in daylight saving time.

For reference, on June 20, the longest day of the year, the Sun rises at 5:30 AM and sets 15 hours, 20 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, 2 minutes later, at 4:38 PM.

Sunrise & Sunset with Twilight in August

Sunrise & Sunset with Twilight in August in Tripoli1815222911223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303031312 AM4 AM6 AM8 AM10 AM12 PM2 PM4 PM6 PM8 PM10 PM12 AMJulSep6:00 AM6:00 AMAug 18:28 PMAug 18:28 PM6:33 AM6:33 AMAug 317:44 PMAug 317:44 PM6:17 AM6:17 AMAug 168:08 PMAug 168:08 PMSolarMidnightSolarMidnightSolarNoonSunriseSunsetNowNow
The solar day over the course of August. 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.


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 Tripoli is rapidly decreasing during August, falling from 45% to 28% over the course of the month.

For reference, on July 20, the muggiest day of the year, there are muggy conditions 48% of the time, while on November 14, the least muggy day of the year, there are muggy conditions 0% of the time.

Humidity Comfort Levels in August

Humidity Comfort Levels in August in Tripoli1815222911223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303031310%10%20%30%40%50%60%70%80%90%100%JulSepAug 145%Aug 145%Aug 3128%Aug 3128%Aug 1141%Aug 1141%Aug 2136%Aug 2136%NowNowoppressiveoppressivemuggymuggyhumidhumidcomfortablecomfortabledrydrymiserablemiserable
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.


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 Tripoli is gradually increasing during August, increasing from 7.9 miles per hour to 8.7 miles per hour over the course of the month.

For reference, on March 31, the windiest day of the year, the daily average wind speed is 12.8 miles per hour, while on August 2, the calmest day of the year, the daily average wind speed is 7.9 miles per hour.

The lowest daily average wind speed during August is 7.9 miles per hour on August 2.

Average Wind Speed in August

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 Tripoli throughout August is predominantly from the south, with a peak proportion of 41% on August 28.

Wind Direction in August

Wind Direction in August in Tripoli1815222911223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303031310%100%20%80%40%60%60%40%80%20%100%0%JulSepNowNowwestsouthnortheast
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).

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 Tripoli typically lasts for 5.6 months (169 days), from around April 19 to around October 6, rarely starting before April 1 or after May 8, and rarely ending before September 19 or after October 22.

The month of August in Tripoli is reliably fully within the growing season.

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

Time Spent in Various Temperature Bands and the Growing Season in August in Tripoligrowing season1815222911223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303031310%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%JulSep100%Aug 16100%Aug 1690%Sep 1990%Sep 19Jul 12100%Jul 12100%NowNowcoldcoolcomfortablewarmhotvery cold
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 percentage of time spent in various temperature bands. 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 Tripoli are rapidly increasing during August, increasing by 602°F, from 1,819°F to 2,421°F, over the course of the month.

Growing Degree Days in August

The average growing degree days accumulated over the course of August, 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 Tripoli is decreasing during August, falling by 1.0 kWh, from 6.6 kWh to 5.5 kWh, over the course of the month.

Average Daily Incident Shortwave Solar Energy in August

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


For the purposes of this report, the geographical coordinates of Tripoli are 42.808 deg latitude, -92.258 deg longitude, and 1,033 ft elevation.

The topography within 2 miles of Tripoli is essentially flat, with a maximum elevation change of 92 feet and an average elevation above sea level of 1,032 feet. Within 10 miles is essentially flat (213 feet). Within 50 miles contains only modest variations in elevation (771 feet).

The area within 2 miles of Tripoli is covered by cropland (77%) and trees (17%), within 10 miles by cropland (96%), and within 50 miles by cropland (94%).

Data Sources

This report illustrates the typical weather in Tripoli 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 4 weather stations near enough to contribute to our estimation of the temperature and dew point in Tripoli.

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

The stations contributing to this reconstruction are: Oelwein Municipal Airport (38%, 27 kilometers, southeast); Waterloo Municipal Airport (31%, 31 kilometers, south); Charles City Municipal Airport (20%, 41 kilometers, northwest); and Decorah Municipal Airport (10%, 67 kilometers, northeast).

Other 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 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.


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.