Presa Plutarco Elias Calles Weather Records (MXN00001018)

The annual mean temperature here has risen by 0.2 C (0.1 to 0.2) per decade over 1934 to 2012. In Fahrenheit: 0.3 F (0.2 to 0.4) per decade. The slope is a straight line fitted to 75 complete years; the brackets give its 95 percent interval.

Across 47 years with a frost, the median last spring frost at Presa Plutarco Elias Calles falls on 15 February and the median first autumn frost on 26 November, which leaves a median of 276 days between them.

Fitted over all years, the growing season changes by +5.5 days per decade at this station.

A day with at least 43.1 mm (1.7 in) of rain is expected about once in 2 years. A day with at least 86.4 mm (3.4 in) of rain is expected about once in 100 years.

The levels come from a generalised extreme value (GEV) distribution fitted by L-moments to the wettest-day total of each year, 79 years of values from 1934 to 2012.

A return level is an estimate. It is least reliable for the long periods, 50 and 100 years, and for any period longer than the record behind the fit, where the fit has to reach past the largest day actually observed. It is not a forecast.

The largest wettest-day totals in the fit: 100.6 mm (4.0 in) in 1987; 97.8 mm (3.9 in) in 1970; 77.5 mm (3.1 in) in 1966.

2 changes were suspected in the annual mean temperature of Presa Plutarco Elias Calles, at 1977 and 2005. Each is measured against neighbouring stations.

• Relative to 5 neighbouring stations, the station's annual mean temperature from 1977 ran 0.6 C (1.2 F) lower than in the years before (likely change).
• Relative to 5 neighbouring stations, the station's annual mean temperature from 2005 ran 0.3 C (0.6 F) lower than in the years before (likely change).