Estonian cultural memory is rich with countless sayings tied to the weather and the seasons. A cold January means a warm summer, March rains promise wet weather through fall — what should we believe and what not? Novaator asked climatologist Ain Kallis from the Environment Agency to assess some spring-related folk wisdom submitted by readers.

You should only walk barefoot outside after the first thunderstorm. That way you can be sure the ground is warm enough.

According to Kallis, thunderstorm statistics show that 94 percent of lightning in Estonia does occur between May and August. However, if we ask when the first thunderstorm of the year typically happens, it's important to note that lightning can strike in any month — even in the depths of winter. For example, between 1821 and 1940, there were 13 thunderstorm days recorded in January and February and 17 in March.

"So this piece of folk wisdom isn't exactly accurate. Of course, it's much more pleasant to walk barefoot in true spring or summer. This year, though, thunderstorm season kicked off with a bang — with a record for April set on the 19th, when 1,697 cloud-to-ground lightning strikes were registered in Lääne-Viru County and South Estonia. In the days that followed, the ground temperature in Tartu County hovered around 25 degrees Celsius," the climatologist explained.

You can only plant potatoes once you can sit on the soil with your bare backside.

"That's actually a very common agrometeorological indicator! This method has been used not only to determine the right time to plant potatoes but also flax. The only issue is that it depends a lot on the type of soil, the location, the potato variety, and of course, the measuring tool used by the tester," Kallis noted.

According to the climatologist, seed potatoes should be planted in warm and dry soil at a depth of about 10 centimeters. For non-sprouted tubers, the soil temperature at that depth needs to be above 8°C. For instance, on Monday, April 21, at 2 p.m. at the Tartu-Tõravere weather station, the surface soil temperature was 22.1°C, at 10 centimeters deep it was 14.9°C and at 15 centimeters deep it was 12.8°C.

You should plant potatoes when the bird cherry tree starts to bloom.

According to Ain Kallis, in addition to anthropological indicators, potato growers should indeed pay attention to the phenological calendar. Data shows that by the time the bird cherry tree is in bloom, the soil has typically warmed up to a suitable temperature. For example, according to the weather service, in Estonia's "spring capital" Türi, the average start of bird cherry blooming is May 19, with the earliest recorded bloom on April 29, 1990 and the latest on June 8, 1955. The blooming begins earliest near the Latvian border and in mainland Estonia and significantly later on the island of Hiiumaa.

At the same time, Kallis says it's worth sticking to another piece of agronomic advice when planting: "It's better to put the tuber in the ground a bit later rather than too early."

If you plant beets before leheristipäev (the Thursday before Ascension Day — ed.), they won't grow.

"I don't have much personal experience with planting beets. In cooler weather, they probably struggle, but a lot also depends on the kind of spring we're having. Plus, leheristipäev, as a movable religious holiday, shifts each year with Easter — it fell on May 22 this year, on May 2 last year and back in 2008 it was as early as April 24, when air temperatures barely reached 10 degrees Celsius," the climatologist noted.

He added that one should keep in mind that on leheristipäev, nothing that grows from the ground or draws nourishment from it should be disturbed. Everything of that sort needs space to breathe. According to Kallis, those who violate this rule on leheristipäev are in for a tough summer battling weeds. In the worst case, everything growing from the earth could become so overgrown that it ends up choking out even the person who didn't give the grass room to breathe that day.

Short-term forecasts tend to be more accurate

According to Ain Kallis, such pieces of folk wisdom and traditional weather lore have developed over centuries out of practical need. Faith in their accuracy persisted for a long time. For example, as late as 1898, one U.S. publication wrote that "every old cow is a better weather prophet than newspaper forecasts."

In Kallis' view, short-term forecasts tend to hold up better in folk wisdom. "For instance, if there's a ring around the moon (or sun), rain and wind are coming — this means a cyclone with a warm front is approaching. If stars are flickering, it points to incoming precipitation, indicating the air has become more humid. If there's heavy dew on the ground in the morning, good weather is likely. Some biometeorologists have even recommended studying links between animal behavior and weather — like if a fox is barking, a snowstorm is on the way. If a titmouse seeks shelter under the eaves, a sudden cold snap is coming," he explained.

Long-term [folk] forecasts, on the other hand, haven't stood up as well against time and scientific advancement. For example, no reliable connection has been found between winter and summer temperatures — whether cold or warm. In fact, Kallis said, a cold winter is more likely to be followed by a chilly, drawn-our spring than a hot summer.

At the same time, linking weather patterns to proverbs and folk calendar dates is difficult, Kallis noted, partly because a calendar reform in 1918 shifted traditional observances by nearly two weeks. 

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