The Estonian Weather Service upgraded its high-temperature warning from "level one" to "level two" on Monday afternoon. A heatwave is expected to last all week.
This morning the agency said the air temperature will rise to between 28 and 31 degrees (c) across the country, but now it is expected to be slightly higher at 32-33 degrees (c).
The level 2 warning means the weather is "dangerous" rather than "potentially dangerous".
"Unusual meteorological phenomena have been forecast. Be very vigilant and keep regularly informed about the weather forecast. Be aware of the risks that might be unavoidable and follow any advice given by authorities," the service advises.
The temperature will be at a similar level, around 30 degrees (c), until Friday.
Rain is forecast on Tuesday and storms on Wednesday.
Editor: Helen Wright