Climate and Average Weather Year Round at Guidonia Italy

At Guidonia, the summers are short, hot, humid, dry, and mostly clear and the winters are long, cold, and partly cloudy. Over the course of the year, the temperature typically varies from 36°F to 91°F and is rarely below 28°F or above 98°F.

Based on the beach/pool score, the best time of year to visit Guidonia for hot-weather activities is from mid June to early September.

The hot season lasts for 2.7 months, from June 17 to September 7, with an average daily high temperature above 83°F. The hottest month of the year at Guidonia is August, with an average high of 89°F and low of 65°F.

The cool season lasts for 4.0 months, from November 18 to March 16, with an average daily high temperature below 61°F. The coldest month of the year at Guidonia is January, with an average low of 37°F and high of 54°F.

At Guidonia, 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 at Guidonia begins around June 8 and lasts for 3.1 months, ending around September 11.

The clearest month of the year at Guidonia is July, during which on average the sky is clear, mostly clear, or partly cloudy 86% of the time.

The cloudier part of the year begins around September 11 and lasts for 8.9 months, ending around June 8.

The cloudiest month of the year at Guidonia is November, during which on average the sky is overcast or mostly cloudy 49% of the time.

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

The wetter season lasts 8.1 months, from September 9 to May 11, with a greater than 21% chance of a given day being a wet day. The month with the most wet days at Guidonia is November, with an average of 9.3 days with at least 0.04 inches of precipitation.

The drier season lasts 3.9 months, from May 11 to September 9. The month with the fewest wet days at Guidonia is July, with an average of 3.5 days with at least 0.04 inches of precipitation.

Among wet days, we distinguish between those that experience rain alone, snow alone, or a mixture of the two. The month with the most days of rain alone at Guidonia is November, with an average of 9.3 days. Based on this categorization, the most common form of precipitation throughout the year is rain alone, with a peak probability of 33% on November 18.

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. Guidonia experiences significant seasonal variation in monthly rainfall.

Rain falls throughout the year at Guidonia. The month with the most rain at Guidonia is November, with an average rainfall of 3.4 inches.

The month with the least rain at Guidonia is July, with an average rainfall of 0.7 inches.

The length of the day at Guidonia varies significantly over the course of the year. In 2024, the shortest day is December 21, with 9 hours, 7 minutes of daylight; the longest day is June 20, with 15 hours, 15 minutes of daylight.

The earliest sunrise is at 5:32 AM on June 14, and the latest sunrise is 2 hours, 4 minutes later at 7:37 AM on January 4. The earliest sunset is at 4:37 PM on December 8, and the latest sunset is 4 hours, 11 minutes later at 8:48 PM on June 27.

Daylight saving time (DST) is observed at Guidonia during 2024, starting in the spring on March 31, lasting 6.9 months, and ending in the fall on October 27.

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

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.

Guidonia experiences significant seasonal variation in the perceived humidity.

The muggier period of the year lasts for 3.6 months, from June 14 to October 2, during which time the comfort level is muggy, oppressive, or miserable at least 11% of the time. The month with the most muggy days at Guidonia is August, with 11.9 days that are muggy or worse.

The least muggy day of the year is February 23, when muggy conditions are essentially unheard of.

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 at Guidonia experiences mild seasonal variation over the course of the year.

The windier part of the year lasts for 2.8 months, from February 1 to April 26, with average wind speeds of more than 6.9 miles per hour. The windiest month of the year at Guidonia is March, with an average hourly wind speed of 7.3 miles per hour.

The calmer time of year lasts for 9.1 months, from April 26 to February 1. The calmest month of the year at Guidonia is August, with an average hourly wind speed of 6.3 miles per hour.

The predominant average hourly wind direction at Guidonia varies throughout the year.

The wind is most often from the south for 1.7 months, from March 22 to May 13 and for 2.6 weeks, from September 19 to October 7, with a peak percentage of 32% on October 6. The wind is most often from the west for 4.2 months, from May 13 to September 19, with a peak percentage of 43% on July 18. The wind is most often from the east for 5.5 months, from October 7 to March 22, with a peak percentage of 38% on January 1.

Guidonia 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 water temperature experiences significant seasonal variation over the course of the year.

The time of year with warmer water lasts for 2.8 months, from June 28 to September 21, with an average temperature above 74°F. The month of the year at Guidonia with the warmest water is August, with an average temperature of 77°F.

The time of year with cooler water lasts for 4.4 months, from December 15 to April 28, with an average temperature below 61°F. The month of the year at Guidonia with the coolest water is February, with an average temperature of 57°F.

To characterize how pleasant the weather is at Guidonia 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 times of year to visit Guidonia for general outdoor tourist activities are from early May to early July and from late August to mid October, with a peak score in the first week of June.

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 Guidonia for hot-weather activities is from mid June to early September, with a peak score in the second week of July.

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.

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 at Guidonia typically lasts for 9.2 months (279 days), from around February 29 to around December 4, rarely starting before February 6 or after March 29, and rarely ending before November 8 or after December 27.

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 at Guidonia should appear around February 28, only rarely appearing before February 13 or after March 18.

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 extreme seasonal variation over the course of the year.

The brighter period of the year lasts for 3.2 months, from May 11 to August 17, with an average daily incident shortwave energy per square meter above 6.5 kWh. The brightest month of the year at Guidonia is July, with an average of 7.5 kWh.

The darker period of the year lasts for 3.6 months, from October 27 to February 15, with an average daily incident shortwave energy per square meter below 2.9 kWh. The darkest month of the year at Guidonia is December, with an average of 1.7 kWh.