  The COVID19 infection is known to disseminate through droplets ejected by
infected individuals during coughing, sneezing, speaking and breathing. The
spread of the infection and hence its menace depend on how the virus-loaded
droplets evolve in space and time with changing environmental conditions. In
view of this, we investigate the evolution of the droplets within the purview
of the Brownian motion of the evaporating droplets in the air with varying
weather conditions under the action of gravity. We track the movement of the
droplets till either they gravitationally settle on the ground or evaporate to
aerosols of size 2$\mu$m or less. Droplets with radii $2 \mu$m or less may
continue to diffuse and remain suspended in the air for long time. The effects
of relative humidity and temperature on the evaporation are found to be
significant. We note that under strong flowing conditions droplets travel large
distances. It is found that the bigger droplets fall on the ground due to the
dominance of gravity over the diffusive force despite the loss of mass due to
evaporation. The smaller evaporating droplets may not settle on the ground but
remain suspended in the air due to the dominance of the diffusive force. The
fate of the intermediate size droplets depends on the weather conditions and
play crucial roles in the spread of the infection. These environment dependent
effects indicate that the maintenance of physical separation to evade the virus
is not corroborated, making the use of face mask indispensable.
