What the averages say
The mean annual temperature is 15.9 °C. The warmest month is August, averaging 24.4 °C with highs around 28.9 °C; the coldest is January, averaging 8.8 °C with lows of 5.7 °C. The 23 degrees between the mean high of August and the mean low of January are the real measure of how continental this climate is.
Heat, cold and extremes
On average, 27 days a year reach 30 °C or more and 4 bring frost. Neither heat nor cold dominates the year. The highest reading in the series is 38.4 °C, set in August, and the lowest -4.7 °C, in January.
Rain, sun and wind
619 mm fall each year over 103 days with measurable rain, an amount with a summer clearly drier than the rest of the year: October is the wettest month with 86 mm and July the driest with 31 mm. The sky is clear on 67 days a year. Mean wind speed is around 15 km/h and mean annual relative humidity 69 %.
Month by month
AEMET climate normals 1991-2020. Barcelona, Fabra observatory, 18.5 km from the centre at 408 m above sea level.| Monthly mean | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
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| Mean temperature | 8.8 | 9.4 | 11.7 | 13.7 | 17.2 | 21.3 | 24.1 | 24.4 | 20.8 | 17.2 | 12.2 | 9.5 |
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| Mean high | 11.8 | 13.0 | 15.6 | 17.8 | 21.5 | 25.7 | 28.6 | 28.9 | 24.9 | 20.6 | 15.3 | 12.2 |
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| Mean low | 5.7 | 5.9 | 7.8 | 9.7 | 12.9 | 16.9 | 19.5 | 19.9 | 16.8 | 13.7 | 9.2 | 6.7 |
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| Rainfall (mm) | 46 | 36 | 54 | 62 | 56 | 32 | 31 | 32 | 81 | 86 | 58 | 46 |
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| Rain days | 8.0 | 6.6 | 8.4 | 10.7 | 10.6 | 7.0 | 6.3 | 7.8 | 9.9 | 10.5 | 9.2 | 7.6 |
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| Days ≥ 30 °C | 0.0 | 0.0 | 0.0 | 0.0 | 0.2 | 3.7 | 11.3 | 10.7 | 1.3 | 0.2 | 0.0 | 0.0 |
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| Frost days | 1.0 | 1.4 | 0.3 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.1 | 0.7 |
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Where this data comes from
These are the 1991-2020 climate normals published by AEMET, the Spanish state meteorological agency, for the Barcelona, Fabra observatory — the nearest official station with a complete series to Terrassa today. One caveat: no station with a complete normal series sits inside Terrassa today, and the nearest one that does is 18.5 km away at 408 m, so these figures describe its surroundings rather than the city itself. A normal is not a forecast: it describes a thirty-year average, and any given day can depart from it widely. For tomorrow, use the forecast at the top of this page.
