Copernicus Report: Precipitation, relative humidity and soil moisture for October 2019
In October 2019 most of western and northern Europe experienced wetter than average conditions, whereas drier than average conditions prevailed in eastern Europe and the Mediterranean region. Japan experienced much above average precipitation related to Typhoon Hagibis, but severe dry conditions prevailed in the western USA, creating a favourable environment for wildfires in the region, and drier than average conditions prevailed in most of the extratropical Southern Hemisphere, particularly in Australia and the southern part of Africa.
The surface hydrological variables are more difficult to observe and analyse than surface temperature. The data on soil moisture are currently of qualitative rather than quantitative value. This summary is intended to provide European and near-global views of conditions for the month. Specific information for many countries can be found on the websites of their weather or climate services.
Europe - October 2019
In October 2019, wetter than average conditions prevailed over large parts of northern and western Europe, as indicated by above average precipitation, soil moisture and relative humidity compared to the 1981-2010 average. This was particularly true over a band encompassing the southern parts of Ireland and the UK, most of France, the Benelux, Germany and most regions around the Baltic Sea. Some areas in the northeast of Spain, south of France and northern Italy experienced very heavy rainfall towards the end of the month.
Exceptions to the wetter-than-average northern and western Europe were Iceland and most of Norway, which saw drier than average conditions in general. In the south of France, soil moisture remained below average despite above average precipitation.
Drier than average conditions also prevailed in most of the Mediterranean region, eastern Europe and around the Black Sea, where soil moisture in particular was much below average.
Europe - Last 12 Months Hydrology Anomalies
For the last 12 months, ending in October 2019, most of Europe saw drier than average conditions, with above average temperature and all three hydrological indicators (precipitation, soil moisture and relative humidity) below their respective 1981-2010 average. During the same period, wetter than average conditions, marked by above average precipitation and soil moisture, prevailed only in eastern Iceland, Ireland, large parts of the UK, western and northern Scandinavia and northern Finland, and some regions along the Mediterranean Sea, including the southernmost parts of Italy, Greece and parts of Turkey. Some regions, such as the Alps, show mixed conditions.
Globe - October 2019 Hydrological Anomalies
Beyond Europe, in the Northern Hemisphere extra-tropics, October 2019 brought wetter than average conditions, with above average precipitation, soil moisture and relative humidity, to large parts of Canada, the northern USA, most of northern Siberia, parts of the middle east, Pakistan and northern India. Precipitation was above average also in the eastern USA and over Japan. Most notably, the latter was hit by typhoon Hagibis which brought large amounts of rain within a short period of time. Dry conditions prevailed over the western USA, where precipitation and even more so soil moisture were lower than average. This provided favourable conditions for the large wildfires that affected parts of California during October.
In the extra-tropical southern hemisphere, drier than average conditions prevailed overall, as has been the case for several months in a row. Most below average were south-eastern Australia, southernmost Africa, as well as large parts of Argentina and Chile and southern Brazil. However, parts of Argentina saw above average precipitation.
Globe - Last 12 Months Hydrological Anomalies
For the 12 months ending in October 2019, precipitation, soil moisture and relative humidity were below average (indicating generally dry conditions) within a belt stretching eastwards from Europe across large parts of Asia. This dry belt includes most of the regions to the north and east of the Black and Caspian Seas, as well as some parts of central Asia, Russia, Mongolia and northern China.
Southern Africa and Australia experienced much drier than average conditions, strengthening severe drought conditions. The exception is the remarkable extreme rainfall in Queensland during the past March, whose imprint is still visible in the 12-month average. Furthermore, in the southern and central parts of South America, conditions were drier than average.
On the contrary, precipitation and relative humidity were higher than average over most of the Middle East, central and eastern China. Generally wet conditions marked by above average precipitation, soil moisture and relative humidity prevailed in southern and eastern USA, Alaska, eastern Canada and central Argentina.
Longer term trends
Monthly Global humidity anomalies
Relative humidity averaged over all land areas globally has decreased over the last forty years and has remained below its 1981-2010 average since the early 2000s. The average relative humidity for October 2019 was also below average, but not by a particularly large amount.
Relative humidity averaged over Europe as a whole is more variable, but in general also shows a net decline over time. Relative humidity for October 2019 in Europe was slightly below average.
The observed drying is not associated with an appreciable reduction in precipitation, as shown below for four European regions. It may be a consequence of a period in which surface air temperature rose faster over land than it did over sea.
Continued monitoring is required to document behaviour over a longer period and refine the understanding of this aspect of climate variability or change.
The variation over time of the hydrological variables and temperature are shown below for averages over land areas for NW, NE, SW and SE Europe. Values are averaged over successive four-month periods in order to highlight variations on seasonal and longer time scales.
Regional differences are quite pronounced in the time series. Average precipitation rates are higher in the north, particularly the NW, but precipitation is more variable in the southern regions. This is partly a consequence of the smaller areas of the southern regions or the four-month averaging. Warming is largest in the NE, but the decrease in relative humidity is larger in the south.
The correlations between precipitation, relative humidity and soil moisture, evident in the maps of anomalies, can be seen to hold for the area averages on time scales up to a year or more. However, average precipitation does not show the marked longer-term decrease seen for relative humidity and soil moisture.
The four months to October 2019 saw somewhat drier than average conditions for NW and SW Europe with average precipitation, below average soil moisture and relative humidity and above average temperature.
The same four months saw drier than average conditions for NE and SE Europe with below average precipitation, soil moisture and relative humidity and above average temperature.
NW Europe Hydro Anomalies
NE Europe Hydro Anomalies
SW Europe Hydro Anomalies
SE Europe Hydro Anomalies