Madrid (CNN) Spain and Portugal faced another exceptionally hot day Saturday as a heat wave that has killed three people in Spain threatened to raise temperatures to record levels.

Large areas of Portugal are on red alert for heat, including the capital, Lisbon. Temperatures will reach 45 degrees Celsius (113 degrees Fahrenheit) in parts of the south-central Alentejo region, according to the country's weather agency, IPMA.

Forecasters at the UK Met Office have said temperatures in the Iberian Peninsula this weekend "could beat the all-time continental European record of 48C," which is a little over 118 degrees Fahrenheit, before the mercury starts to dip.

That record was set in the Greek capital, Athens, in July 1977. The record for Spain is 47.3 Celsius, while for Portugal it's 47.4 Celsius, according to the World Meteorological Organization.

The Spanish Ministry of Health on Friday confirmed three deaths this week due to the hot weather.

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