Climate Change Chart of Death Valley National Park, USA

Overview of climate changes

Temperature changes

Averaged across calendar months, monthly mean temperature shows a difference of +3.07 °C compared with the earlier reference period. This is a comparison of monthly means, not daytime maximum temperatures, and it summarizes the months rather than describing every month individually. The largest monthly increase was in January, at a difference of +5.76 °C; that identifies the strongest increase, not a uniform change throughout the year.

Changes in rainfall

Mean daily rainfall averaged across calendar months had a difference of -0.02 mm/day compared with the earlier period. This unweighted summary of monthly means is not a day-weighted annual average or a monthly rainfall total, and it does not mean that rainfall decreased in every month. The largest monthly increase occurred in August, with a difference of +0.34 mm/day, while the largest monthly decrease was in February, at a difference of -0.29 mm/day. These contrasting monthly differences show why the average change should be read as an aggregate, rather than as a description of each month's rainfall.

Changes in sunshine duration

Mean daily sunshine duration, expressed in hours per day, had an average difference across calendar months of -0.04 hours/day. This unweighted average of monthly means describes an overall comparison, not the result for every month. The largest increase was in February, with a difference of +0.52 hours/day; the largest decrease was in July, at a difference of -0.30 hours/day. The opposing monthly differences put the small overall average in context without implying a consistent change in daily sunshine throughout the year.

Changes in snowfall

Mean daily snowfall averaged across calendar months shows a difference of -0.49 mm/day compared with the earlier reference period. This is an unweighted comparison of monthly means, not a day-weighted annual average or a monthly total, and it does not imply that snowfall decreased in every month. The largest monthly decrease occurred in December, at a difference of -1.67 mm/day. These figures describe recorded snowfall differences and should be understood as averages and a monthly extreme, rather than a uniform change across the calendar.