San Jose Weather Records (USC00047821)

The annual mean temperature here has risen by 0.2 C (0.2 to 0.3) per decade over 1893 to 2025. In Fahrenheit: 0.4 F (0.4 to 0.5) per decade. The slope is a straight line fitted to 107 complete years; the brackets give its 95 percent interval.

Across 64 years with a frost, the median last spring frost at San Jose falls on 8 February and the median first autumn frost on 10 December, which leaves a median of 305 days between them.

In 1938 to 2021 the median growing season was 319 days. That is 33 days more than in 1893 to 1932.

Fitted over all years, the growing season changes by +8.9 days per decade at this station.

A day with at least 34.0 mm (1.3 in) of rain is expected about once in 2 years. A day with at least 89.3 mm (3.5 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, 116 years of values from 1893 to 2025.

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: 109.7 mm (4.3 in) in 1918; 91.4 mm (3.6 in) in 1968; 81.8 mm (3.2 in) in 1962.

2 changes were suspected in the annual mean temperature of San Jose, at 1940 and 1958. Each is measured against neighbouring stations.

• Relative to 5 neighbouring stations, the station's annual mean temperature from 1940 ran 0.3 C (0.5 F) higher than in the years before (likely change).
• Relative to 5 neighbouring stations, the station's annual mean temperature from 1958 ran 0.3 C (0.6 F) lower than in the years before (possible change).