Long-term temperature monthly average time series (1916-2017) at the Izaña Observatory

The Observatory at Izaña has a series of meteorological records that this year (2017) has marked 102 years.

We have produced graphs of long-term monthly average temperature time series, corresponding to an extensive summer period (June-September) by month (each series corresponds to a specific month) of these 103 years. On these graphs we have included the statistics (percentiles, medians and extremes) of the reference series 1961-90, which is the reference period used for climate change studies.

The records show that the 4 months making up the extensive summer period (June, July, August and September) of 2017 maintain the trend towards warming, and are significantly above the 1961-90 median.

The data for June 2017 stands out with an average monthly temperature of 17.2 °C. which not only exceeds the maximum of the 1961-90 series, but constitutes an absolute record for the complete series 1916-2017, and higher than the 17.1 °C recorded in June 2000.

Temperatures in July 2017 were not as outstanding as those in the previous year, although with a monthly average of 18.9 °C, close to the 75th percentile of the 1961-90 time series, it remains anomalously warm in relation to this reference.

In August 2017 the monthly average, at 20.0 °C, is again clearly above the 90th percentile of the 1961-90 time series. In fact, it equals the 2nd overall position for the entire August time series with August 1967, 2008 and 2009; only exceeded by the 20.5 °C in August 1988.

Finally, in September 2017 the average monthly temperature, with 15.6 °C, maintains the very warm characteristics of summer 2017, almost coinciding with the 90th percentile of the 1961-90 series.