Reykjavik Weather Records (IC000004030)

The annual mean temperature here has risen by 0.2 C (0.1 to 0.2) per decade over 1949 to 2025. In Fahrenheit: 0.3 F (0.1 to 0.4) per decade. The slope is a straight line fitted to 77 complete years; the brackets give its 95 percent interval.

Across 77 years with a frost, the median last spring frost at Reykjavik falls on 14 May and the median first autumn frost on 3 October, which leaves a median of 142 days between them.

In 1996 to 2025 the median growing season was 149 days. That is 7 days more than in 1949 to 1978.

Fitted over all years, the growing season changes by +2.6 days per decade at this station.

A day with at least 29.8 mm (1.2 in) of rain is expected about once in 2 years. A day with at least 49.4 mm (1.9 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, 50 years of values from 1949 to 1999.

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: 49.2 mm (1.9 in) in 1959; 48.2 mm (1.9 in) in 1989; 44.7 mm (1.8 in) in 1967.

2 changes were suspected in the annual mean temperature of Reykjavik, at 1976 and 1993. Each is measured against neighbouring stations.

• Relative to 4 neighbouring stations, the station's annual mean temperature from 1976 ran 0.3 C (0.6 F) lower than in the years before (likely change).
• Relative to 4 neighbouring stations, the station's annual mean temperature from 1993 ran 0.2 C (0.4 F) higher than in the years before (possible change).