Climate Change Chart of San Jose, USA

Overview of climate changes

Temperature changes

Averaged across calendar months, monthly mean temperature shows a difference of +2.36 °C. This unweighted comparison of monthly means describes the overall average difference, not a change experienced in every month or a continuous trend. The largest monthly increase was in June, at +5.23 °C, while December had the largest decrease, with a difference of -1.10 °C. These month-specific results show that the comparison varies by calendar month; monthly means are not daytime maximum temperatures.

Changes in rainfall

Mean daily rainfall, rather than monthly rainfall totals, had an unweighted difference averaged across calendar months of -0.55 mm/day. This summarizes the differences between monthly averages and does not imply the same change in each month. The largest monthly decrease occurred in February, with a difference of -2.30 mm/day. By contrast, September recorded the largest monthly increase, at +0.17 mm/day. Together, these month-specific differences illustrate why the across-month mean should not be read as a uniform month-by-month result.

Changes in sunshine duration

Mean daily sunshine duration had an unweighted difference averaged across calendar months of -0.01 hours/day. This small overall difference summarizes the monthly averages and should not be taken to mean that sunshine shifted equally in every month. The largest decrease was in March, with a difference of -0.41 hours/day, whereas February had the largest increase, at +0.23 hours/day. These contrasting monthly changes sit alongside the near-zero across-month mean; the measure is average daily hours, not a monthly total.

Changes in snowfall

Mean daily snowfall shows an unweighted difference averaged across calendar months of +0.01 mm/day. The small difference at the displayed precision does not establish that snowfall was unchanged beyond that precision. The largest monthly increase occurred in February, with a difference of +0.08 mm/day. These figures describe mean daily amounts, not monthly snowfall totals, and the month-specific increase need not characterize other months.