Weather with thaw and frosty weather in a flat and foothill zone comes since the beginning of November, but usually in the first and second decades of November they make insignificant percent and only in the third decade their repeatability considerably increases, and repeatability of not droughty weather considerably decreases. In a mountain zone wind speed increases.
From the North the Araratsky valley is limited to the massif Aragats and spurs of Tsakhkuniksky ridge on which most southern suburb a volcanic cone Arai-ler, Gegamsky mountains, and from the southeast spurs of Zangezursky and ridges in the east tower. The hollow of the Average Araks Current shares on three parts — the Yerevan, Nakhichevan and Dzhulfinsky hollows. The last two are small on the area.
In general winter near the Araratsky valley cold, low-snow with prevalence of cold cloudy weather. With a place height raising snow cover becomes steady and long, and clear days increases.
In April in all area the noticeable growth of bezmorozny cloudy and rainy weather and as condensation level in April is still rather low is observed, in a mountain zone repeatability of and rainy weather is not great, their maximum is observed in the second half of spring.
Thus, if the spring and summer come since the beginning in low-lying part of a hollow and then extend on mountain areas, the fall and winter, on the contrary, at first come in a mountain zone, and then gradually go down.
Strongly developed convective currents lift heated air in the top zones of mountains, causing noticeable warming. But the biggest warming in a mountain zone is observed at powerful occurrences of continental tropical air from the South. These factors with local heating cause cases of moderate and droughty weather at the heights of 3000 — 3500 m of the southern slope of the massif Aragats while on a northern slope this weather higher than 2500 m are never observed.
Approach of winter in the area happens not at the same time. In the top zone of mountains frosty weather happens at the beginning of October, and at the beginning of November becomes prevailing. In the second decade of October average daily temperatures pass through 0 ° and at the end of October the winter mode of weather is set.
As it was stated above, in winter vertical temperature gradients considerably decrease that is the main reason for an of mountain and valley circulation. In the conditions of local areas of pressure thermal inversions often develop.
Frosts in the Araratsky plain and in the foothills stop in the first half of April, at average heights of mountains at the beginning of May, and in a zone at the end of June. It should be noted that the latest in the Araratsky plain are observed in May (Yerevan), at heights of mountains in June (N. Akht, and in a mountain zone frosts do not happen only in August.
The maximum of repeatability of sukhoveyno-droughty weather in the Dzhulfinsky hollow, from where to the northwest and to the southeast it gradually decreases. Repeatability of cloudy and droughty weathers with increase in height of a place, on the contrary, quickly grows. Sukhoveyno-zasushlivaya weather disappears at the heights of 1500 — 2000m, and even above also repeatability of moderate and droughty weather which stops at tops of mountains where frosty weathers are possible in the summer decreases.
In March cloudy weather that is connected by the beginning of development of convection increases in the afternoon. But in March types of weathers with rather low air temperatures everywhere prevail. Low temperatures at the beginning of spring are caused still by rather small inflow of heat and existence of snow cover for which thawing there is a considerable part of the arriving heat.
In zones low-lying and average heights of mountains in March repeatability frosty is sharply reduced by N of Thaw weather, is considerable repeatability of slightly overcast bezmorozny weather, and also warm cloudy and rainy weather that is connected with frequent passing through these regions of cyclones.
The cool air which is climbing down mountains softens a heat. It is favored also by night cooling. Therefore evenings and nights in the Araratsky plain as we already spoke, happen cool thereof daily fluctuations of air temperature and humidity increase.