mistral (noun) -
1. a strong north wind that blows in France during the winter

Source: WordNet ® 1.7, © 2001 Princeton University

The mistral had an effect on Vincent Van Gogh and his paintings as evidenced by this:
http://www.vangoghgallery.com/painting/p_0712.htm, among others. It is also said to cause headaches and a general feeling of malaise http://www.hedweb.com/bgcharlton/depression.html
Why is this so?
http://watershed.net/negions_n_health.htm

Since this article is a long one, here are some of the pertinent paragraphs:
Turning to the adverse effects associated with certain ion environments, there have been long traditions in the folklore of nearly every country that link certain changes in weather with changes in health and behaviour. One such tradition has to do with the winds of ill repute, for example, the Foehn (Southern Europe), Sirocco (Italy), Santa Ana (United States), Khasmin (Near East), and Mistral (France). Wherever they prevail, their victims attribute to them the ability to induce respiratory distress of various sorts, nervousness, headache and a multitude of other ills. So malign is their influence that when they blow, judges deal leniently with crimes of passion, surgeons postpone elective surgery and teachers expect more than the usual fractiousness from their students.

Since the turn of the century, several scientists and physicians have hypothesised that the immediate cause of such malaise is the upset in electrical balance of the atmosphere that precedes or accompanies the winds. This relationship between air ions and disease, tenuous at first, is finding support in the meteorological observations of investigators such as Robinson and Dirnfield who studied the Sharav, a weather complex afflicting the Near East and characterised by persistent wind, a rapid rise in temperature and a fall in relative humidity. Robinson and Dirnfield measured solar radiation, temperature and relative humidity, wind velocity and direction and the electrical state of the atmosphere before, during and after the Sharav. They found that 12 - 36 hours before the characteristic changes in wind, temperature and humidity, the total number of ions increased (from 1500 ions/cm3 to 2600 ions/cm3) and the ratio of positive to negative ions jumped from the normal 1.2 to 1.33. This early shift in ion density and ratio coincided with the onset of nervous and physical symptoms in weather sensitive people and was considered the only meteorological change that could be responsible for the discomfort associated with the Sharav [32].