Map from Google - Macedonia

In the Republic of Macedonia, the climate is cold in winter and hot in summer. The continentality of the climate is due to the fact that the country has no outlet to the sea, and in addition it's separated from the Adriatic and Aegean Seas by mountain ranges. The major cities are located at hill altitudes, often in valleys, which enhance the cold in winter (because cold air stagnates on the ground), as well as the summer heat. The Balkan Peninsula is exposed to cold waves from the north or east, and Macedonia is no exception. The north-west wind which blows in the valley of the Vardar is called Vardarec, an equivalent to the Bora, maybe a little less violent.
The climate becomes milder in the far south-east, near Lake Dojran, where there are cities like Gevgelija and Valandovo: actually, it becomes almost Mediterranean, because the area is located south of the mountain ranges that insulate the country from the sea.
In the mountain areas, in particular the Shar mountains in the north-west and the Baba mountains in the south-west, which both exceed 2,500 metres (8,200 feet), the climate naturally becomes colder, with heavy snowfalls in winter, and afternoon thunderstorms in summer. In general, at a given altitude, the temperatures in winter are similar to those of the Alps.
Here are the average temperatures of the capital Skopje, located in the north, at 250 metres (800 ft) above sea level.
Average temperatures - Skopje
SkopjeJanFebMarAprMayJunJulAugSepOctNovDec
SkopjeJFMAMJJASOND
Min (°C)-4-125101315151161-2
Max (°C)481419242730302620115
Min (°F)253036415055595952433428
Max (°F)394657667581868679685241

Precipitation is not abundant in the valleys, where it amounts to about 500 millimetres (20 inches) per year, while it becomes a bit more abundant with increasing altitude. In general, the two rainiest seasons are late spring and autumn, while winter and summer are relatively dry.
Here is the average precipitation in Skopje.
Average precipitation - Skopje
SkopjeJanFebMarAprMayJunJulAugSepOctNovDecYear
SkopjeJFMAMJJASONDY
Prec. (mm)403030405545303035605555505
Prec.(in)1.61.21.21.62.21.81.21.21.42.42.22.219.9
Days75658542468666

Winter in Macedonia is generally cold, although the temperature varies with altitude. The average temperature in January is around freezing (0 °C or 32 °F) at the lowest altitudes. In Skopje, which as mentioned is located at 250 metres (800 ft) above sea level, the average in January is 0 °C (32 °F). The winter weather is not always stable: calm periods, where cold air clings to the soil, alternate with mild days, in which warm air masses from the Mediterranean manage to penetrate in the country, and with periods of intense cold, due to outbreaks of air masses coming from Russia, in which the temperature can plunge to -20 °C (-4 °F).

Summer is hot in the valleys located at lower altitudes (eg in Skopje), where the maximum temperatures are usually around 30 °C (86 °F). The temperature range is high and moisture is not high, so nights are usually cool, but days can be torrid, with peaks of 40 °C (104 °F). Sunshine is frequent, and the rains are relatively rare, occurring in the form of thunderstorms in the afternoon.

Skopje

When to go

The best time to visit the Republic of Macedonia goes from May to September. In Skopje and other cities located in the lowlands, the months of July and August (and sometimes the second half of June) can be really hot, so you may prefer May, June and September. September is usually a sweet month, sunny and with little rain.

What to pack

In winter: warm clothes, sweater or fleece, 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.