Then God said, “Let the water under the sky be gathered into one place, and let the dry land appear.” And it was so. Genesis 1:9 (HCSB)
Located on the far southeastern edge of the Indochinese peninsula, Vietnam as a country has a familiar ‘S-shaped’ boundary. Vietnam covers approximately 331,688 square kilometers (slightly larger than the state of New Mexico in the U.S.A.). With larger areas in the north and south, its shape is long and narrow in the middle. It stretches 1,650 kilometers from north to south (a little over 1,000 miles) and is only 50 kilometers (31 miles) across at its most narrow point.
Vietnam is bordered by Cambodia and Laos to the west and China to the north. The east faces the Gulf of Tonkin and the South China Sea. Geographically, Vietnam can be seen as having four primary separate regions. The Red River Delta in the north, the Central Highlands in the middle, the narrow eastern coastline and the Mekong River Delta in the south.
The Red River Delta is a level region of about 3,000 square kilometers. It is smaller but more intensely developed and more densely populated than the Mekong River Delta. The highlands and mountain plateaus in the north and northwest are inhabited mainly by tribal minority groups. The Central Highlands (Tay Nguyen) cover approximately 51,800 square kilometers of rugged mountain peaks, extensive forests, and rich soil in the center part of the country. The narrow, flat coastal lowlands extend from south of the Red River Delta to the Mekong River basin. The Mekong River delta is approximately 40,000 square kilometers of a low plain barely above sea level in most places.
Vietnam has a tropical monsoon climate, with humidity averaging 84 percent throughout the year. However, because of differences in latitude and the marked variety of topographical relief, the climate tends to vary considerably from place to place. During the winter or dry season, extending roughly from November to April, the monsoon winds usually blow from the northeast along the China coast and across the Gulf of Tonkin, picking up considerable moisture; consequently the winter season in most parts of the country is dry only by comparison with the rainy or summer season. During the southwesterly summer monsoon, occurring from May to October, the heated air of the Gobi Desert rises, far to the north, inducing moist air to flow inland from the sea and deposit heavy rainfall.
Annual rainfall is substantial in all regions and torrential in some, ranging from 120 centimeters to 300 centimeters. Nearly 90 percent of the precipitation occurs during the summer. The average annual temperature is generally higher in the plains than in the mountains and plateaus. Temperatures range from a low of 5°C in December and January, the coolest months, to more than 37°C in April, the hottest month. Seasonal divisions are more clearly marked in the northern half than in the southern half of the country, where, except in some of the highlands, seasonal temperatures vary only a few degrees, usually in the 21°C-28°C range.(portions of this page taken directly from Ronald J. Cima, ed. Vietnam: A Country Study. Washington: GPO for the Library of Congress, 1987. Found at this link: http://countrystudies.us/vietnam/33.htm )