In Bulgaria, the climate is generally continental, with cold winters and warm or hot summers; it is slightly milder along the coast of the Black Sea, and of course colder in hills and mountains.
The country is exposed to both cold air masses from northern Europe or Russia, and warm air masses from the Mediterranean or North Africa; in the south, the Rhodope Mountains, which somewhat separate it from Greece, are able to partly block the southern currents, however, the most intense heat waves can surpass them and then invade the country.

In Bulgaria there are two plains, divided by the chain of the Balkan Mountains (or Stara Planina), stretched from west to east. North of the mountains, in the Danube Plain, separated from Romania by the river of the same name, where cities like Ruse and Pleven are found, the average temperature is around -1°C (30 °F) in January, and 22 °C (72 °F) in July, while south of the Balkans, the Thracian Plain, where cities like Plovdiv and Stara Zagora are found, is slightly warmer, with an average temperature of 1 °C (34 °F) in January, and 23 °C (73 °F) in July. The Danube Plain is more exposed to cold waves, because the Balkans partly block the northern winds, so that the cold records in the Danube Plain of the past 20 years are around -25 °C (-13 °F), while in the Thracian Plain they hover around -15 °C (5 °F).
Here are the average temperatures of Plovdiv.
Average temperatures - Plovdiv

Plovdiv	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Plovdiv	J	F	M	A	M	J	J	A	S	O	N	D
Min (°C)	-2	0	2	7	12	16	17	17	13	8	2	0
Max (°C)	4	6	11	17	22	27	29	28	25	18	10	6
Min (°F)	28	32	36	45	54	61	63	63	55	46	36	32
Max (°F)	39	43	52	63	72	81	84	82	77	64	50	43

In the east, the narrow coastal strip is milder, being influenced by the Black Sea: in this area, where cities like Varna and Burgas are located, winters are cold but not too much, with average temperatures a few degrees above freezing (but cold waves caused by cold winds of Siberian origin are possible here as well), and summers are warm or even hot, but tempered by sea breezes. In the south-eastern part of Bulgaria, south of Burgas and towards the Turkish border, the climate gets even milder.
Average temperatures - Varna

Varna	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Varna	J	F	M	A	M	J	J	A	S	O	N	D
Min (°C)	-1	0	2	7	12	16	18	18	14	10	6	2
Max (°C)	6	7	10	15	20	25	27	27	24	18	13	8
Min (°F)	30	32	36	45	54	61	64	64	57	50	43	36
Max (°F)	43	45	50	59	68	77	81	81	75	64	55	46

The Black Sea is acceptable for swimming in summer, especially in July and August, and reaches 24 °C (75 °F) in August, while it's still a little cool in June.
Sea temperature - Varna

Varna	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Varna	J	F	M	A	M	J	J	A	S	O	N	D
Sea (°C)	7	7	7	10	15	20	23	24	22	18	13	10
Sea (°F)	45	45	45	50	59	68	73	75	72	64	55	50

In the south-west, the valley of the Struma, towards the border with Greece, has a climate a bit milder than the plains: the city of Sandanski has a fairly cold winter, with possible frosts (the January average is 2.5 °C or 36.5 °F), and hot summers (the July average is 24 °C or 75 °F).

The capital Sofia is located at 550 metres (1,800 ft) of altitude, in a valley, in a position which enhances cold air stagnation in winter, and in some cases the summer heat as well. The city is located south of the western part of the Balkan range, but in this part the mountains are not very high, so they don't protect much the city from cold air masses; in addition, due to the altitude, the city is often the coldest city of Bulgaria. Here the average in January is -1.5 °C (29.5 °F). In summer, however, Sofia is cooler than the plains because of altitude: the average temperature in July is 20 °C (68 °F), even though sometimes it can be hot, with peaks of 35/37 °C (95/99 °F) from June to August, while nights are almost always cool and pleasant.
Average temperatures - Sofia

Sofia	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Sofia	J	F	M	A	M	J	J	A	S	O	N	D
Min (°C)	-5	-3	0	5	10	12	14	14	11	6	2	-3
Max (°C)	2	4	9	15	20	24	26	26	23	17	10	4
Min (°F)	23	27	32	41	50	54	57	57	52	43	36	27
Max (°F)	36	39	48	59	68	75	79	79	73	63	50	39

The mountainous areas have a cold climate, and the temperatures are similar, at a given altitude, to those of the southern side of the Alps. You can ski until the end of March in Borovets and Pamporovo.

Precipitation in Bulgaria is not abundant, because the country is sheltered from the westerlies, which discharge most of the rains over the Adriatic coast: precipitation amounts to around 500/600 millimetres (20/23.5 inches) per year in the plains, and even less, below 500 mm (20 in) in the coastal north-east area (see Varna), which is therefore quite arid, while it becomes a bit more abundant in the mountains.
In winter, precipitation is not abundant in the lowlands, but it's quite frequent, and often occurs in the form of snow. The rainiest months are May and June, because of thunderstorms, which can occur in the afternoon; they become less frequent in coastal areas, while they are more frequent and abundant in mountainous areas. Typically, August and September experience poor rains, but even October is often a dry month, at least in plains and in Sofia.
Here is the average precipitation in Plovdiv.
Average precipitation - Plovdiv

Plovdiv	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec	Year
Plovdiv	J	F	M	A	M	J	J	A	S	O	N	D	Y
Prec. (mm)	50	40	45	45	70	65	50	35	40	45	55	60	600
Prec.(in)	2	1.6	1.8	1.8	2.8	2.6	2	1.4	1.6	1.8	2.2	2.4	23.6
Days	7	7	7	7	9	8	6	5	4	5	6	8	79

Winter, from December to February, is cold throughout the country. Cold air often stagnates on the plains, with cloudy skies and light snowfalls, but these periods may be interrupted by warm wind invasions from the south, which can raise the temperature to 15 °C (59 °F) and more, and more frequently by of cold air outbreaks from Russia, which can bring strong winds followed by severe frosts.

Spring, from March to May, is not very rainy, but it experiences great changes in temperature, especially in March and April, due to clashes of air masses, so that the first warm days alternate with the return of cold weather, in which there can be some late snow showers. Usually, from mid-April or May, temperatures in the plains begin to be mild or warm in a more stable way. In May, in fine weather, afternoon thunderstorms begin to occur.

Summer, from June to August, is warm, or even hot, especially in inland plains: the heat is intense in the lowlands, especially at a distance from the sea. Highs are normally around 30/32 °C (86/90 °F), but hot days, with peaks of 40 °C (104 °F), are not so rare.
In coastal areas, the heat is less intense and tempered by the breeze.

Autumn, from September to November, starts as a mild and pleasant season, with rare rains. In general, there is a fairly sharp turn during the month of October, when colder air masses begin to circulate, but the rains are certainly not as plentiful as on the Mediterranean coast of the Balkan Peninsula, given that the country is not directly exposed to western or southern winds.



The sun in Bulgaria shines regularly in summer, especially in the plains and along the coast, although clouds may form in the afternoon, which may lead to thunderstorms. In winter, on the other hand, the sun is not very present.
Here are the average daily sunshine hours in Plovdiv.
Sunshine - Plovdiv

Plovdiv	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Plovdiv	J	F	M	A	M	J	J	A	S	O	N	D
Sun (hours)	3	4	5	7	8	9	11	10	8	5	4	2

Having a continental climate, Bulgaria may be visited in spring and autumn, from mid-May to mid-June, when it must be put into account some thunderstorms in the afternoon, and from mid-September to mid-October, a bit cooler but also drier. For those who can stand the heat, summer can also be good, remembering that the cities located in inland plains like Plovdiv and Pleven, can be hot in July and August.
In Sofia, the summer heat is slightly cooled by altitude. From May to August, some afternoon thunderstorms are possible, which become gradually less frequent, so that the rainy days are 9 in May, 8 in June, 7 in July and 6 in August. In July and August, however, sometimes it can get hot during the day. In September, it rains on average only four days, and the temperatures are pleasant.
The Rose Valley, from Karlovo to Kazanlak, is located at about 400 metres (1,300 feet) above sea level, south of the Balkan Mountains, and in the flowering period, from mid-May to mid-June, it has warm days and cool nights, and possible thunderstorms in the afternoon.
The coastal areas of Bulgaria (see Sunny Beach, Golden Sands) can be a pleasant place to stay in summer (July and August), for a beach holiday. Every so often, some showers or thunderstorms can occur in the afternoon, but more rarely than in inland areas. September is still nice and sunny.


In winter: warm clothes, sweater, down jacket, hat, gloves and scarf, raincoat or umbrella.
In summer: light clothes, T-shirt, but also long pants, light jacket and sweatshirt for the evening; umbrella.