The KNMI meteorological institute issued a code yellow weather warning covering the entire country for much of Friday morning, and a second warning covering most of the afternoon and evening. The warning was issued as the temperature in De Bilt, Utrecht, rose above 30 degrees Celsius, marking the first official tropical weather day for the Netherlands this year.

The thermometer reached 30.5 degrees at 2:30 p.m. Thursday in De Bilt, considered the country’s meteorological center and headquarters of the KNMI. A high of 31 degrees was forecast and the temperature dropped slightly under heavy cloud cover to 30.1 just before 3 p.m.

The storm warning mentions the possibility of lightning and hail, accompanied by wind gusts of up to 75 kilometers per hour. The first warnings start at midnight in the southern provinces, with code yellow being activated for the northern provinces a few hours later. This will last until noon, depending on the location. Most of the country will also be on a warning from around 2 p.m. to around midnight, the KNMI said.

People are advised to take shelter from advancing storms, but not to hide under trees. Areas of open water should also be avoided while the warning is in effect. Drivers should also be careful on the roads, as the pavement is expected to become slippery due to heavy rains after a relatively long dry spell. This will be complicated by the strong gusts that will accompany the thunderstorms.

The low temperature early Friday morning will likely be 18 to 21 degrees. Later, the mercury will peak at 30 degrees in Utrecht and Gelderland, and 32 degrees in Limburg. A break in the heat will come on Saturday with lows of 16 to 19 degrees and highs of 23 degrees.

It will likely rise to 29 degrees on Sunday.