A cold snap over the weekend caused problems on the roads and for air travelers in northern Greece. Thessaloniki’s Macedonia international airport canceled five flights on Saturday and nine planes were unable to land because thick fog had seriously reduced visibility. The airport was operating normally yesterday. Snow fell in much of northern and central Greece, reaching 20 centimeters in Trikala. Authorities did their best to clear roads, spreading large quantities of salt, but motorists were advised to attach anti-skid chains to their car tires. Temperatures yesterday dropped to -5 Celsius (23 Fahrenheit) in parts of northern Greece. Sunny weather early yesterday melted snow in many parts but a new drop in temperatures late yesterday was expected to bring fresh snowfall.