During the past two weeks, temperatures across the state have been warmer than normal, as much as 0-8 degrees above average. Northwest Iowa has had the largest departure from normal during this time period. Spotty precipitation has fallen across the state in the past 14 days, with southeast Iowa receiving the largest amounts at around 1 inch. Despite that, the entire state is below average for precipitation during the last 14 days. North-central Iowa has the greatest two-week deficit at 2 inches below normal.
Soil moisture is starting to dry out, especially with warm air temperatures, low dew points, and wind. However, soil moisture is still looking better than the past couple of years at this point. NASS crop progress reports show the topsoil moisture is at 70 percent adequate and the subsoil moisture at 67 percent adequate.
Dew point temperatures across the state were around 30-45 degrees between May 1st through the 10th. A blocking pattern has determined the weather during the first half of May. A persistent high pressure has existed over the state, keeping us warm and dry.
Dew point temperature is the temperature that air needs to cool at constant pressure to reach saturation. Essentially, dew point temperature is the temperature at which, when saturation is reached, dew could begin forming. It provides a measure of the moisture in the atmosphere. Relative humidity is the ratio of the actual mixing ratio of the air to the saturation mixing ratio at the same temperature and pressure. Dew point temperature tells you more about how dry or humid it may feel outside. Higher dew points feel muggier and lower dew points feel drier in the summer. Here is an example from the National Weather Service:
General comfort levels USING DEW POINT that can be expected during the summer months:
- less than or equal to 55: dry and comfortable
- between 55 and 65: becoming "sticky" with muggy evenings
- greater than or equal to 65: lots of moisture in the air, becoming oppressive
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- Weather and Climate Extension Specialist