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Average Weather in Quincy Illinois, United States

In Quincy, the summers are warm, humid, and wet; the winters are very cold and windy; and it is partly cloudy year round. Over the course of the year, the temperature typically varies from 22°F to 88°F and is rarely below 4°F or above 96°F.

Based on the tourism score, the best time of year to visit Quincy for warm-weather activities is from late May to late September.

Climate Summary

very coldcoldcoolwarmhotwarmcoolcoldJanFebMarAprMayJunJulAugSepOctNovDec70%70%45%45%clearovercastprecipitation: 4.2 inprecipitation: 4.2 in1.1 in1.1 inmuggy: 59%muggy: 59%0%0%drydrytourism score: 6.6tourism score: 6.60.20.2
Click on each chart for more information.

Temperature

The hot season lasts for 3.7 months, from May 28 to September 19, with an average daily high temperature above 78°F. The hottest day of the year is July 20, with an average high of 88°F and low of 69°F.

The cold season lasts for 3.0 months, from November 28 to February 28, with an average daily high temperature below 47°F. The coldest day of the year is January 22, with an average low of 22°F and high of 37°F.

Average High and Low Temperature

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 entire year of hourly average temperatures. The horizontal axis is the day of the year, the vertical axis is the hour of the day, and the color is the average temperature for that hour and day.

Average Hourly Temperature

Average Hourly Temperature in QuincyJanFebMarAprMayJunJulAugSepOctNovDec12 AM4 AM8 AM12 PM4 PM8 PM12 AMfreezingfreezingvery coldcoldcoldcoolcoolcomfortablewarmhotvery coldfreezingfreezing
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.

Daejeon, South Korea (6,626 miles away) is the far-away foreign place with temperatures most similar to Quincy (view comparison).

Clouds

In Quincy, the average percentage of the sky covered by clouds experiences significant seasonal variation over the course of the year.

The clearer part of the year in Quincy begins around June 12 and lasts for 4.4 months, ending around October 26. On August 26, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 70% of the time, and overcast or mostly cloudy 30% of the time.

The cloudier part of the year begins around October 26 and lasts for 7.6 months, ending around June 12. On February 12, the cloudiest day of the year, the sky is overcast or mostly cloudy 55% of the time, and clear, mostly clear, or partly cloudy 45% of the time.

Cloud Cover Categories

Cloud Cover Categories in QuincyclearercloudiercloudierJanFebMarAprMayJunJulAugSepOctNovDec0%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%Aug 2670%Aug 2670%Feb 1245%Feb 1245%Jun 1258%Jun 1258%Oct 2658%Oct 2658%clearmostly clearpartly 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.

Precipitation

A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in Quincy varies throughout the year.

The wetter season lasts 6.1 months, from March 27 to September 29, with a greater than 26% chance of a given day being a wet day. The chance of a wet day peaks at 40% on June 7.

The drier season lasts 5.9 months, from September 29 to March 27. The smallest chance of a wet day is 12% on January 26.

Among wet days, we distinguish between those that experience rain alone, snow alone, or a mixture of the two. Based on this categorization, the most common form of precipitation throughout the year is rain alone, with a peak probability of 40% on June 7.

Daily Chance of Precipitation

Daily Chance of Precipitation in QuincywetdrydryJanFebMarAprMayJunJulAugSepOctNovDec0%10%20%30%40%50%60%70%80%90%100%Jun 740%Jun 740%Jan 2612%Jan 2612%Jan 115%Jan 115%Mar 2726%Mar 2726%Sep 2926%Sep 2926%rainsnow
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 months and not just the monthly totals, we show the rainfall accumulated over a sliding 31-day period centered around each day of the year. Quincy experiences significant seasonal variation in monthly rainfall.

Rain falls throughout the year in Quincy. The most rain falls during the 31 days centered around May 27, with an average total accumulation of 4.2 inches.

The least rain falls around January 20, with an average total accumulation of 0.8 inches.

Average Monthly Rainfall

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.

Snowfall

We report snowfall in liquid-equivalent terms. The actual depth of new snowfall is typically between 5 and 10 times the liquid-equivalent amount, assuming the ground is frozen. Colder, drier snow tends to be on the higher end of that range and warmer, wetter snow on the lower end.

As with rainfall, we consider the snowfall accumulated over a sliding 31-day period centered around each day of the year. Quincy experiences some seasonal variation in monthly liquid-equivalent snowfall.

The snowy period of the year lasts for 3.8 months, from November 20 to March 13, with a sliding 31-day liquid-equivalent snowfall of at least 0.1 inches. The most snow falls during the 31 days centered around January 29, with an average total liquid-equivalent accumulation of 0.3 inches.

The snowless period of the year lasts for 8.2 months, from March 13 to November 20. The least snow falls around July 23, with an average total liquid-equivalent accumulation of 0.0 inches.

Average Liquid-Equivalent Monthly Snowfall

The average liquid-equivalent snowfall (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 rainfall.

Sun

The length of the day in Quincy varies significantly over the course of the year. In 2018, the shortest day is December 21, with 9 hours, 20 minutes of daylight; the longest day is June 21, with 15 hours, 1 minute of daylight.

Hours of Daylight and Twilight

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 is at 5:36 AM on June 14, and the latest sunrise is 2 hours, 1 minute later at 7:36 AM on November 3. The earliest sunset is at 4:40 PM on December 8, and the latest sunset is 3 hours, 58 minutes later at 8:38 PM on June 27.

Daylight saving time (DST) is observed in Quincy during 2018, starting in the spring on March 11, lasting 7.8 months, and ending in the fall on November 4.

Sunrise & Sunset with Twilight and Daylight Saving Time

Sunrise & Sunset with Twilight and Daylight Saving Time in QuincyJanFebMarAprMayJunJulAugSepOctNovDec12 AM2 AM4 AM6 AM8 AM10 AM12 PM2 PM4 PM6 PM8 PM10 PM12 AMJun 145:36 AMJun 145:36 AM8:38 PMJun 278:38 PMJun 27Dec 84:40 PMDec 84:40 PM7:36 AMNov 37:36 AMNov 3Mar 11DSTMar 11DSTDSTNov 4DSTNov 4daynightnightnightnightSolarMidnightSolarMidnightSolarNoonSunriseSunset
The solar day over the course of the year 2018. 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. The transitions to and from daylight saving time are indicated by the 'DST' labels.

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.

Quincy experiences extreme seasonal variation in the perceived humidity.

The muggier period of the year lasts for 3.7 months, from May 27 to September 18, during which time the comfort level is muggy, oppressive, or miserable at least 15% of the time. The muggiest day of the year is July 22, with muggy conditions 59% of the time.

The least muggy day of the year is December 9, when muggy conditions are essentially unheard of.

Humidity Comfort Levels

Humidity Comfort Levels in QuincymuggyJanFebMarAprMayJunJulAugSepOctNovDec0%10%20%30%40%50%60%70%80%90%100%Dec 90%Dec 90%Jul 2259%Jul 2259%May 2715%May 2715%Sep 1815%Sep 1815%oppressiveoppressivemuggymuggydrydrycomfortablecomfortable
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.

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 Quincy experiences significant seasonal variation over the course of the year.

The windier part of the year lasts for 7.3 months, from October 11 to May 21, with average wind speeds of more than 9.7 miles per hour. The windiest day of the year is April 1, with an average hourly wind speed of 12.1 miles per hour.

The calmer time of year lasts for 4.7 months, from May 21 to October 11. The calmest day of the year is August 5, with an average hourly wind speed of 7.3 miles per hour.

Average Wind Speed

Average Wind Speed in QuincywindywindyJanFebMarAprMayJunJulAugSepOctNovDec0 mph2 mph4 mph6 mph8 mph10 mph12 mph14 mph16 mph18 mphApr 112.1 mphApr 112.1 mphAug 57.3 mphAug 57.3 mphOct 119.7 mphOct 119.7 mphMay 219.7 mphMay 219.7 mph
The average of mean hourly wind speeds (dark gray line), with 25th to 75th and 10th to 90th percentile bands.

The predominant average hourly wind direction in Quincy varies throughout the year.

The wind is most often from the north for 1.6 months, from February 15 to April 2, with a peak percentage of 31% on March 8. The wind is most often from the south for 8.0 months, from April 2 to December 2, with a peak percentage of 40% on June 21. The wind is most often from the west for 2.5 months, from December 2 to February 15, with a peak percentage of 35% on January 1.

Wind Direction

Wind Direction in QuincyWNSWJanFebMarAprMayJunJulAugSepOctNovDec0%100%20%80%40%60%60%40%80%20%100%0%westsouthnortheast
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).

Best Time of Year to Visit

To characterize how pleasant the weather is in Quincy throughout the year, we compute two travel scores.

The tourism score favors clear, rainless days with perceived temperatures between 65°F and 80°F. Based on this score, the best time of year to visit Quincy for general outdoor tourist activities is from late May to late September, with a peak score in the last week of August.

Tourism Score

Tourism Score in Quincybest timeJanFebMarAprMayJunJulAugSepOctNovDec02468106.66.60.20.26.26.26.06.0 precipitationprecipitationcloudscloudstemperaturetemperaturetourism score
The tourism score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).

The beach/pool score favors clear, rainless days with perceived temperatures between 75°F and 90°F. Based on this score, the best time of year to visit Quincy for hot-weather activities is from late June to late August, with a peak score in the third week of July.

Beach/Pool Score

Beach/Pool Score in Quincybest timeJanFebMarAprMayJunJulAugSepOctNovDec02468105.95.90.00.0 precipitationprecipitationcloudscloudstemperaturetemperaturebeach/pool score
The beach/pool score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).

Methodology

For each hour between 8:00 AM and 9:00 PM of each day in the analysis period (1980 to 2016), independent scores are computed for perceived temperature, cloud cover, and total precipitation. Those scores are combined into a single hourly composite score, which is then aggregated into days, averaged over all the years in the analysis period, and smoothed.

Our cloud cover score is 10 for fully clear skies, falling linearly to 9 for mostly clear skies, and to 1 for fully overcast skies.

Our precipitation score, which is based on the three-hour precipitation centered on the hour in question, is 10 for no precipitation, falling linearly to 9 for trace precipitation, and to 0 for 0.04 inches of precipitation or more.

Our tourism temperature score is 0 for perceived temperatures below 50°F, rising linearly to 9 for 65°F, to 10 for 75°F, falling linearly to 9 for 80°F, and to 1 for 90°F or hotter.

Our beach/pool temperature score is 0 for perceived temperatures below 65°F, rising linearly to 9 for 75°F, to 10 for 82°F, falling linearly to 9 for 90°F, and to 1 for 100°F or hotter.

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 Quincy typically lasts for 6.7 months (205 days), from around April 7 to around October 29, rarely starting before March 21 or after April 24, and rarely ending before October 10 or after November 18.

Time Spent in Various Temperature Bands and the Growing Season

Time Spent in Various Temperature Bands and the Growing Season in Quincygrowing seasonJanFebMarAprMayJunJulAugSepOctNovDec0%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%50%Apr 750%Apr 750%Oct 2950%Oct 2990%Apr 2490%Apr 2490%Oct 1090%Oct 1010%Mar 2110%Mar 2110%Nov 1810%Nov 180%Dec 220%Dec 22Jul 13100%Jul 13100%frigidfreezingvery coldcomfortablewarmhotcoolcold
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.

Based on growing degree days alone, the first spring blooms in Quincy should appear around March 26, only rarely appearing before March 12 or after April 14.

Growing Degree Days

Growing Degree Days in QuincyJanFebMarAprMayJunJulAugSepOctNovDec0°F500°F1,000°F1,500°F2,000°F2,500°F3,000°F3,500°F4,000°FMar 2688°FMar 2688°FJun 5900°FJun 5900°FJul 121,800°FJul 121,800°FDec 314,003°FDec 314,003°F
The average growing degree days accumulated over the course of the year, 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 experiences significant seasonal variation over the course of the year.

The brighter period of the year lasts for 4.0 months, from April 29 to August 27, with an average daily incident shortwave energy per square meter above 5.9 kWh. The brightest day of the year is July 2, with an average of 6.9 kWh.

The darker period of the year lasts for 3.2 months, from November 3 to February 10, with an average daily incident shortwave energy per square meter below 2.9 kWh. The darkest day of the year is December 21, with an average of 1.9 kWh.

Average Daily Incident Shortwave Solar Energy

Average Daily Incident Shortwave Solar Energy in QuincybrightdarkdarkJanFebMarAprMayJunJulAugSepOctNovDec0 kWh1 kWh2 kWh3 kWh4 kWh5 kWh6 kWh7 kWh8 kWh9 kWhJul 26.9 kWhJul 26.9 kWhDec 211.9 kWhDec 211.9 kWhApr 295.9 kWhApr 295.9 kWhAug 275.9 kWhAug 275.9 kWhFeb 102.9 kWhFeb 102.9 kWh
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 Quincy are 39.936 deg latitude, -91.410 deg longitude, and 545 ft elevation.

The topography within 2 miles of Quincy contains only modest variations in elevation, with a maximum elevation change of 220 feet and an average elevation above sea level of 542 feet. Within 10 miles also contains only modest variations in elevation (305 feet). Within 50 miles contains only modest variations in elevation (584 feet).

The area within 2 miles of Quincy is covered by artificial surfaces (66%), water (18%), and cropland (10%), within 10 miles by cropland (76%), and within 50 miles by cropland (77%) and trees (19%).

Data Sources

This report illustrates the typical weather in Quincy, 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 Quincy.

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

The stations contributing to this reconstruction are: Quincy Regional Airport (50%, 19 kilometers, east); Hannibal Regional Airport (36%, 24 kilometers, south); Keokuk Municipal Airport (10%, 58 kilometers, north); and Kirksville Regional Airport (4.4%, 98 kilometers, west).

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.