Today and tomorrow (Thursday April 18) temperatures are due to climb by five or six degrees.
Inland this will mean a maximum of around 21 or 22degC but with coastal areas two or three degrees cooler.
This will still be warmer than normal for mid-April.
Pollen levels are due to be high for Friday to Sunday across East and West Sussex.
The Met Office says there is some uncertainty for the second half of the Bank Holiday.
A band of rain and cooler weather will be waiting in the wings to move across Sussex from the north-east but at the moment it’s not known exactly when it’ll arrive.
As far as the rest of April is concerned, the Met Office says: “Thereafter, for the remainder of April the weather looks set to become generally more changeable across the UK with showers or longer spells of rain, as well as some periods with stronger winds. Despite this, there will be some drier and brighter interludes at times and overall, temperatures should be around average for the end of April.
“As it often the case at this time of year, there may be some marked variations in temperature across the country.”