Why weather changes occur? The reason is that the Sun heat one side side of a planet while the other side cools down at night. The difference in temperature causes changes in pressure, precipitation, and air density. That is why the Sun is the major driver of weather.
The diurnal cycle of rainfall in the UK is shown below. We see that for many years the amount of precipitation increases in the morning and close to the evening and decreases at midday.
Convective rainfall is common in the Pacific Island countries because they are located in the area where the surface of the earth is almost at right angle to the sun and the area of water is the highest. This causes water to evaporate and leads to convective rainfalls.