On average across the year, no, Vietnam is not hotter than Cameroon . Vietnam has an average temperature of 26°C/79°F and Cameroon has an average temperature of 27°C/81°F.
Vietnam's hottest month is June, with an average maximum temperature of 34°C/93°F, which is not hotter than Cameroon's hottest month (April, with an average maximum temperature of 36°C/97°F).
On average across the year, yes, Vietnam is colder than Cameroon . Vietnam has an average minimum temperature of 22°C/72°F and Cameroon has an average minimum temperature of 22°C/72°F.
Vietnam's coldest month is January, with an average minimum temperature of 17°C/63°F, which is colder than Cameroon's coldest month (also January, with an average minimum temperature of 18°C/64°F).
On average across the year, no, Vietnam has less rain than Cameroon. Vietnam has an average annual rainfall of 825mm and Cameroon has an average annual rainfall of 848mm.
Vietnam's wettest month is October, with an average monthly rainfall of 134mm, which is drier than Cameroon's wettest month (August, with an average monthly rainfall of 202mm).