Figures for the first 18 days of the month, show that maximum temperatures dropped by 1.6 degrees Celsius when compared with existing averages.
Southern Portugal has also been considerably cooler, with three days out of the first 18 being four degrees lower than averages.
Despite a considerable increase in temperatures predicted for the beginning of July, especially in southern Portugal, the extended forecasts for the remainder of July indicate that highs will remain below the average.
This comes after last month was confirmed as the second rainiest June in the last 18 years.
However, the results were considered normal by the national Met Office.
According to the Met Office, the rainiest June on record was in 2007.
The average temperature last month was of around 25 degrees Celsius, which the Met Office did say was lower than normal, and a cold snap was registered between 1 and 13 June.