The weather in Bulgaria is influenced mostly
by the Atlantic, European and Mediterranean climate zones resulting
in four distinct seasons:
- white winter (January - February): Temperatures
can drop to -15° C (it is warmer higher up in mountains than
in flatlands and closed valleys); The snow cover is from January
to the first half of February (from December to April at the
north slopes of higher mountains).
The country is invaded by cold Siberian anticyclonic
air masses with prevailing N and NE winds with sunshine in high
mountains above the strong ground inversions bellow. In the flatlands
and especially in closed valleys the inversions may trap Stratus
clouds and cause periods of 3-5 days without sunshine.
The flying is best in higher mountains where naked
trees and rocks produce thermals. Flatlands are also working and
can be better choice when mountains are covered by low clods. Around
the seacoast and 50 km inside the climate is influenced by the warmer
in winter Black Sea - snow cover is for very few days and pilots reported
20-30 km XC flights from 200-300 high hills. Some sites may become
better for soaring in winter because of the more stable and dense
Usually the begining of XC season starts after
the first half of February.
- energetic spring (March-May): The weather is changeable
because of fighting cold north and warm south air masses. The temperatures
rise and can reach 20-30°C but still cold in the night. The
snow is mostly in mountains but until March short snow revenges
can surprise the lower valleys and flatlands.
Sometimes the country is visited by weak cyclones
from Turkish or Italian Mediterranean which can regenerate in the
area and cause 3-4 days of rainy weather. The humidity is increased
and when combined with the night ground inversions can obscure the
closed valleys with stratus clouds.
In March the prevailing winds are from the N quarter.
Local falling gravity winds might be created by the snow covered
The ground inversions are burning out in March
and the snow covered mountains provide an excellent temperature
gradient with 5-8 m/s strong thermals (often blue or with 2500
- 3000 m amsl high cloudbases). Forests are naked and also release
thermals. April and first half of May may have days with strong
south winds (no problem for Sopot) which create waves over
the mountains and still have good temperature gradient (there
were several flights of over 100 km in this conditions).
From the second half of May until the first half
of June the atmosphere becomes more unstable with bigger chances
of Cumulo Nimbuses but still flyable before their development -
usualy later in the afternoon. The most reliable XC flying periods
are in March/April and April/May but generally the weather in spring
is difficult to predict. At the beginning of May a pilot reached
a record cloudbase of more than 4300 m amsl (it happened in Koniavo
in south winds). The more unstable atmosphiere sometimes makes
flatlands better choice for spring XC.
The colder sea and much warmer land are producing
strong sea breeze winds and good seacoast soaring conditions. In
spring were also registered good convergences (between humid
and cold sea breeze and humid and cold NW winds) along the seacoast
when some coastal height gain records (1100 m amsl) were
- hot and dry summer (June-September) Most of the
summer is influenced by the high pressure systems from Mediterranean
and about every 2 weeks is refreshed by quick cold fronts from cyclones
from NW Europe or by small local cyclones (mostly around the
beginnings of June and September). This and the plenty of northern
winds minimize the stable inversion days. Temperatures reach 35°C
and nights are warm in flatlands and cool in mountain areas. In
the beginning of June there might be more Cumulo Nimbuses but later
they become less, isolated (mostly in mountain areas), weaker
and slow growing (which allows use them quite confidently).
High altitude flights (4000 m amsl) were
made in slow growing Cu congestus clouds. Cloudbases are about 2500
m amsl but pilots registered over 4000 m amsl in mountain areas. The
typical NW and NE winds in July and August bring cooler air aloft
(thus good gradient and 3-6 m/s strong thermals) and most
big flights and records were set then (including three flights
of more than 200 km). Everything works good - mountains, their
north slopes, flatlands.
Surprisingly sea breeze can be strong and persistent in August.
- autumn up and down (October - December) The weather
in autumn is mostly influenced by the big cyclones and fronts from
NW Europe and the warm south airmasses preceding them. The first
longer periods of bad weather (up to 1 week) usualy come
in October but even later in November there could be long periods
(up to 2 weeks) of gypsi summer. The second half of November
and beginning of December may be foggy and rainy. Strong inversions
start to fill up the flatlands and closed valleys and good thermal
days become rarer. The typical south winds in the autumn produce
excellent wave conditions in mountain areas. Around sea coast, rivers
and lakes fog may form.
After the furthest parts of SW Europe, the climate
of Bulgaria is one of the best in Europe and provides big variety
of flying conditions (thermals, cross-country, waves, ridge and
see breeze soaring). This combined with the various landscape
(2-3000 m high mountains, hills, flatlands and seacoast)
makes Bulgaria interesting for all year round flying.
The weather in Sopot is not much different to
the rest of Bulgaria. The bad weather and frontal systems usualy
come from west and they reach Sopot a day later compared to west
The Rose Valley between Stara
planina mountain and Sredna Gora mountain is more stable
for thermals in the autumn and winter compared with E Bulgaria.
In the rest of the time Sopot area usualy has the most and best
thermals and XC conditions compared to rest of Bulgaria.
Due to high mountain Sopot is well protected
from NE and S-SW winds and it remained flyable even when the
rest of Bulgaria is too windy. If the NW winds are less than 10-15
m/s (measured at Botev peak) then the local valley-mountain
circulation can prevail the main wind and make Sopot flyable. If
until 12-13 p.m. the N and NW wind at take off doesn't stop then
it is unlikely to be flyable the whole day. If the NW wind is more
than 5-7 m/s at the take off around 10-11 a.m. then it's better
to go to Kliment or Plovdiv area.
When trying long XC E or W along the mountain
range then aware the possible falling winds at Beklemeto,
Shipka, Tvarditza. In winter/spring these falling winds are stronger
due to the colder snow covered mountains.
The local Cb generators are Bogdan (in
Sredna Gora), Vezhen and Botev peaks. After their full development
the Bogdan Cb usually goes E along Sredna Gora, The Vezhen Cb can
go SE in the valley or E toward Sopot, the Botev Cb can stay in
one place or go E, W, S. Around Bania and Karnare it can be more
safe from neighbouring Cb's but aware their gust fronts.