Feb
Taken from the wikipedia:
“Barcelona has a Mediterranean climate, with sub-mediterranean influence, which makes of it not to be the “classical mediterranean climate” with mild, humid winters and warm, dry summers.
Barcelona is located in the eastern coast of the Iberian Peninsula, so, the usual west winds, especially in winters, which cause the wet climate in many places of Western Europe, arrive in Barcelona with low humidity, producing no rain. However, the proximity to the Atlantic, its latitude, and the relief, are the reasons why the summers are not as dry as in other Mediterranean Basin countries, because lows (not surface lows but high-atmospheric “cold invasions”) can affect easily the area of Barcelona (and Catalonia), causing great storms, particularly in August. Some years, the beginning of June is still cool and rainy, like April and May which, together with August, September, October and November, are the wettest months of the year. The driest are July, February, March and June. So, on average, rainy seasons are spring and autumn, and the dry ones are winter and summer. The order is: AUT-SPR-WIN-SUM. We also have to take into account that the Western Mediterranean Climate is the most irregular of the world. This means that in many occasions averages are not what really happens. For instance, one year October can be very dry and July or February wet months. That's the irregularity. Barcelona and London have the same annual rainfall, but London's climate isn’t as irregular and torrential as Barcelona's.
As for temperatures, December, January and February are the coldest months, averaging temperatures of 9°C (48 °F) at the Airport and over 10°C in the city. July and August are the hottest months, averaging temperatures of 24°C (72°F). The highest recorded maximum temperature in the centre of the city is 38.6°C.[16] The coldest recorded minimum temperature was -6,7 °C on the 11th of February 1956 and -5°C the 12th of January 1985. However, in the XIX century -9,6°C were recorded in January 1896. At the Fabra Observatory, situated on the Tibidabo hill, 412 m above the sea level the record summer temperature is C 39.8°C (103.6 °F)[17] on the 7th July 1982, and the lowest temperature ever registered -10'0º the 11th February 1956. Near the hills and the Airport annual rainfall reaches the 650 mm, and in the city centre about 600 mm.”
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All in all, it can be 25ºC maximum and 16ºC minimum but as said above, humidity can give the feeling of being hotter.
In any case, you should also take a light jacket for the evening and an umbrella or raincoat because it may also rain in June.
We’re not located in a banana republic, as some tourists sometimes think.
Answer:
Climate stats for June:
Max: 25 degrees C
Min: 18 degress C
Rain: 37 mm
Answer:
Probably hot and humid. Hotter than the actual temp, because of the humidity. I was there in June a few years ago, and I was just dripping the entire time.
Answer:
summer, with high humidity.