Ciudad Hidalgo (Smn) Weather Records (MXN00016152)

The fitted trend in annual mean temperature here over 1923 to 1987 is -0.06 C (-0.13 to 0.02) per decade. The interval includes zero, so the trend is not clearly different from zero. In Fahrenheit: -0.10 F (-0.24 to 0.04) per decade. The slope is a straight line fitted to 58 complete years; the brackets give its 95 percent interval.

Across 30 years with a frost, the median last spring frost at Ciudad Hidalgo (Smn) falls on 6 February and the median first autumn frost on 2 December, which leaves a median of 301 days between them.

Fitted over all years, the growing season changes by +5.2 days per decade at this station.

A day with at least 41.8 mm (1.6 in) of rain is expected about once in 2 years. A day with at least 92.5 mm (3.6 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, 64 years of values from 1923 to 1987.

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: 81.3 mm (3.2 in) in 1929; 81.0 mm (3.2 in) in 1969; 79.8 mm (3.1 in) in 1986.

One change was suspected in the annual mean temperature of Ciudad Hidalgo (Smn), at 1952. Each is measured against neighbouring stations.

• Relative to 5 neighbouring stations, the station's annual mean temperature from 1952 ran 0.4 C (0.7 F) higher than in the years before (likely change).