Climate trends in indices for temperature and precipitation across New York State , 1948 – 2008

New York State (NYS) is a geographically diverse area susceptible to climate change, but trends in climate extreme indicators have not been extensively studied. Our objectives are to describe temporal and spatial trends in various extreme indicators and their sensitivity to climate change and to demonstrate geographic differences in indicator trends in NYS. We analyzed data from the US Historical Climatology Network for NYS from 1948 to 2008. We assessed trends in 15 temperature and 11 precipitation indicators using linear regression with bootstrapping in SAS and RClimDex software. The indicators showing the most substantial change per decade were frost days (−0.97 days per decade) and diurnal temperature (−0.11°C). For precipitation indicators, the number of heavy precipitation days (+0.99 days), consecutive wet days (+ 0.42 days), the total wet day precipitation (+30.19 mm), and the simple daily intensity index (+0.18 mm/day) showed the most change per decade. The most representative indicators that showed significant trends for more than half of the stations were number of cool nights, diurnal temperature, and number of frost days and increase in total wet day precipitation and simple daily intensity index for precipitation. The most sensitive regions for changes in extreme indicators were the eastern and Great Lakes regions of NYS. In light of these consistent temporal trends of warming and increasing precipitation in NYS with large geographic variation, the indicators that have been identified should be further evaluated and assessed for their health impact. Geographical differences in climate trends may be of use in informing policy and resource allocation for climate change adaptation.