Average Weather in Ílhavo Portugal

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In Ílhavo, the summers are warm, dry, and mostly clear and the winters are cold, wet, and partly cloudy. Over the course of the year, the temperature typically varies from 44°F to 78°F and is rarely below 36°F or above 89°F.

The warm season lasts for 3.3 months, from June 18 to September 28, with an average daily high temperature above 74°F. The hottest day of the year is July 29, with an average high of 78°F and low of 61°F.

The cool season lasts for 3.6 months, from November 21 to March 8, with an average daily high temperature below 62°F. The coldest day of the year is January 23, with an average low of 44°F and high of 58°F.

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.

In Ílhavo, 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 Ílhavo begins around June 8 and lasts for 3.2 months, ending around September 14. On July 20, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 87% of the time, and overcast or mostly cloudy 13% of the time.

The cloudier part of the year begins around September 14 and lasts for 8.8 months, ending around June 8. On December 16, 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.

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

The wetter season lasts 8.1 months, from September 23 to May 27, with a greater than 21% chance of a given day being a wet day. The chance of a wet day peaks at 37% on October 29.

The drier season lasts 3.9 months, from May 27 to September 23. The smallest chance of a wet day is 4% on July 21.

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 37% on October 29.

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. Ílhavo experiences extreme seasonal variation in monthly rainfall.

The rainy period of the year lasts for 11 months, from August 16 to July 1, with a sliding 31-day rainfall of at least 0.5 inches. The most rain falls during the 31 days centered around December 27, with an average total accumulation of 4.8 inches.

The rainless period of the year lasts for 1.5 months, from July 1 to August 16. The least rain falls around July 19, with an average total accumulation of 0.3 inches.

The length of the day in Ílhavo varies significantly over the course of the year. In 2017, the shortest day is December 21, with 9 hours, 16 minutes of daylight; the longest day is June 21, with 15 hours, 5 minutes of daylight.

The earliest sunrise is at 6:03 AM on June 14, and the latest sunrise is 1 hour, 57 minutes later at 8:00 AM on October 28. The earliest sunset is at 5:07 PM on December 7, and the latest sunset is 4 hours, 2 minutes later at 9:09 PM on June 27.

Daylight saving time (DST) is observed in Ílhavo during 2017, starting in the spring on March 26, lasting 7.1 months, and ending in the fall on October 29.

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 perceived humidity level in Ílhavo, as measured by the percentage of time in which the humidity comfort level is muggy, oppressive, or miserable, does not vary significantly over the course of the year, staying within 4% of 4% throughout.

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 predominant average hourly wind direction in Ílhavo varies throughout the year.

The wind is most often from the east for 2.6 weeks, from January 18 to February 5 and for 4.0 weeks, from November 26 to December 24, with a peak percentage of 33% on December 17. The wind is most often from the north for 8.5 months, from February 5 to October 22 and for 3.6 weeks, from November 1 to November 26, with a peak percentage of 62% on July 24. The wind is most often from the south for 1.4 weeks, from October 22 to November 1 and for 3.6 weeks, from December 24 to January 18, with a peak percentage of 29% on October 29.

Ílhavo 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 some seasonal variation over the course of the year.

The time of year with warmer water lasts for 4.2 months, from June 13 to October 18, with an average temperature above 63°F. The day of the year with the warmest water is August 7, with an average temperature of 65°F.

The time of year with cooler water lasts for 3.6 months, from December 27 to April 15, with an average temperature below 58°F. The day of the year with the coolest water is February 18, with an average temperature of 56°F.

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 15 to August 21, with an average daily incident shortwave energy per square meter above 6.7 kWh. The brightest day of the year is July 5, with an average of 7.9 kWh.

The darker period of the year lasts for 3.6 months, from October 25 to February 15, with an average daily incident shortwave energy per square meter below 3.1 kWh. The darkest day of the year is December 25, with an average of 1.8 kWh.

For the purposes of this report, the geographical coordinates of Ílhavo are 40.600 deg latitude, -8.667 deg longitude, and 56 ft elevation.

The topography within 2 miles of Ílhavo contains only modest variations in elevation, with a maximum elevation change of 230 feet and an average elevation above sea level of 53 feet. Within 10 miles also contains only modest variations in elevation (449 feet). Within 50 miles contains only modest variations in elevation (4,514 feet).

The area within 2 miles of Ílhavo is covered by cropland (59%), artificial surfaces (19%), and trees (11%), within 10 miles by cropland (28%) and trees (27%), and within 50 miles by water (43%) and trees (33%).

This report illustrates the typical weather in Ílhavo, 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 2 weather stations near enough to contribute to our estimation of the temperature and dew point in Ílhavo.

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

The stations contributing to this reconstruction are: Francisco de Sá Carneiro Airport (57%, 72 kilometers, north) and Monte Real Mil. (43%, 88 kilometers, south).

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.