Climate Change Chart of Reykjavík, Iceland

Overview of climate changes

Temperature changes

Averaged across calendar months, monthly mean temperature shows a difference of +1.22 °C compared with the earlier reference period; this is an unweighted mean of the monthly differences, not a day-weighted annual average or a measure of daytime highs. The largest monthly increase was in February, with a difference of +2.67 °C. That monthly peak sits alongside the broader mean and does not imply the same increase in every month.

Changes in snowfall

Mean daily snowfall—not monthly totals—was higher on average across calendar months, with a difference of +1.74 mm/day compared with the earlier reference period; this is an unweighted mean of monthly differences, not a day-weighted annual average. The largest monthly increase was in February, at a difference of +6.51 mm/day, while the largest decrease was in April, at a difference of -0.73 mm/day. The positive average does not imply an increase in every month.

Changes in rainfall

Mean daily rainfall, rather than monthly totals, was higher on average across calendar months, with a difference of +0.53 mm/day compared with the earlier reference period; this is an unweighted mean of monthly differences, not a day-weighted annual average. The largest monthly increase was in May, at a difference of +1.37 mm/day, while the largest monthly decrease was in December, at a difference of -0.57 mm/day. These contrasting monthly changes show why the average should not be read as a description of every month.

Changes in sunshine duration

Mean daily sunshine duration averaged across calendar months had a difference of -0.77 hours/day compared with the earlier period, an unweighted mean of monthly differences rather than a day-weighted annual average. The largest monthly decrease occurred in June, with a difference of -2.63 hours/day; by contrast, December had the largest monthly increase, at a difference of +0.30 hours/day. The overall mean therefore summarizes the calendar-month pattern and does not mean sunshine decreased in every month.