Country Overview For Portugal
The climate in Portugal is typically maritime temperate; cool and rainy in north, warmer and drier in south. The terrain: mountainous north of the Tagus River, rolling plains in south. For Lisbon in January the daily average maximum temperatures is 14°C with the average minimum 6°C, while in June the average maximum is 23°C with a minimum of 14°C. The wettest month for Lisbon is November with an average of 159.9mm of precipitation falling while the driest month is July with 17.4mm falling.
HISTORICAL MONTHLY AVERAGES FOR MAY
The information presented below gives detailed historical monthly average weather conditions along with exceptional weather occurrences. To maintain relevance to current weather trends the displayed information has been calculated using data collected over the past two decades. The climate profile is taken from closest available data source to Porto.
Throughout the month of May daytime temperatures will generally reach highs of around 19°C that's about 66°F. At night the average minimum temperature drops down to around 11°C, that's 51°F.
In recent times the highest recorded temperature in May has been 34°C that's 93°F, with the lowest recorded temperature 4°C, about 39°F.
The average daily relative humidity for May is around 78%.
The Heat Index is a measure of how hot it feels when relative humidity is added to actual air temperature. From this a comfort level is calculated providing categories on how heat conditions might adversely affect someone.
Comfort Levels: Given average maximum temperatures and humidity levels generally you should not anticipate any discomfort from heat (see heat index for more information).
The average monthly amount of precipitation has been recorded at around 69 mm, that's 3 inches. Throughout the month you can expect to see rain or drizzle falling on 15 days of the month.
Estimated Hours of Sunshine per Day
We calculate sunshine hours per day using our past forecast data. For May expect the sun to shine for an average of 11 hours per day. This represents the average number of hours in the daytime that the sun is visible and not obscured by cloud e.g. the average number of hours the sun is actually out and shining. Note we calculate hours of sunshine per day using our past forecast data, not observation data, thus it is an estimate and not actual.
The average daily wind speed in May has been around 10 km/h, that’s the equivalent to about 6 mph, or 6 knots. In recent years the maximum sustained wind speed has reached 83 km/h, that’s the equivalent of around 52 mph, or 45 knots.
On average the month of May is affected by foggy conditions on 3 days.
SWIMMING AND WATER TEMPERATURE
The temperature of water an individual will feel comfortable in is very much personal preference. What feels unbearably cold to one person for a swim might be fine for another. We have created our own Swimming Water Temperature Index offering a guide to water temperature and comfort levels for swimming;
In May, for the nearest coastal location, the temperature of the sea averages around 16°C, that's 61° Fahrenheit. Our index indicates for swimming this is considered cool and for most would feel bracing to say the least. The more hardy among us may enjoy a quick dip.
YEARLY TRENDS: WEATHER AVERAGES & EXTREMES
The following charts show yearly weather trends with information on monthly weather averages and extremes.
The chart below plots the average high and low temperature for each month of the year. It also shows the maximum and minimum recorded temperatures.
The chart below plots the average monthly precipitation amount.
The chart below plots the average number of days in any month that you can expect to see rain falling.
The chart below plots the average daily wind speed you can expect for any month. It also shows the maximum recorded sustained wind speed for each month.