Trends in air temperature and precipitation for Canada and north‐eastern USA

Using the univariate, non‐parametric, Kendall's test for monotonic trends from the 1949 to 1989 period, monthly maximum, minimum, average temperature, and precipitation data of some carefully selected stations in Canada and north‐eastern USA, it is found that western Canada for the past 40 years has experienced significant warming in January and March, and to a limited extent in April, May, and June, but virtually no warming trend was detected in eastern Canada and north‐eastern USA. Instead, some cooling trends were found, particularly in October. The analysis on the annual cycle of temperature data also shows the seasonal and regional nature of warming and cooling trends. Unlike temperature, no obvious trend is found in the precipitation data, but on the whole there are more stations (up to 10 per cent) with upward trends (increase in precipitation) during springs and summers. A bivariate test was used to detect a shift in the mean of precipitation series with respect to maximum temperature series but no obvious indication of such a shift was detected.