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Gulf stream collapse
Visby has a humid continental climate (Dfb) according to the Köppen climate classification, influenced by its location on the island of Gotland in the Baltic Sea. Summers are warm, though cooler than on the mainland due to the surrounding water masses, with average highs of around 22 to 26 C. This cooling effect is most noticeable in the spring and early summer, but as summer goes on and the Baltic warms, it becomes less pronounced. Nights are fairly mild, particularly in the latter part of summer, hovering between 14 and 18 C. Still, temperatures can be expected to fall to or below 10 C on a few clear, calm nights. Cooler periods feature daytime temperatures of around 20 C with passing showers that produce most summer rainfall, and nights in the 10 to 14 C range. On the flip side, heatwaves occur every year, generating sunny and calm conditions, and temperatures of 27 to 30 C, with the hottest days hovering between 30 and 33 C. Owing to its maritime location, tropical nights become fairly common under such conditions, occurring 10-15 times per year. "Högsommardagar" (high/peak summer days) above 25 C occur on 35 days a year, while temperatures above 30 C are seen on 6. In general, highs above 20 C is the norm from early to mid-June to the beginning of September. Sea surface temperatures range from 12 C in early June to 22 C by mid-August.

Winters are cold and snowy, with temperatures similar to the Swedish mainland as maritime influence vanishes when the Baltic freezes over. Daytime highs remain below 0 C for an average of 118 days, being the norm from the second half of November to the second half of March. They typically hover around -4 to -6 C, with nights falling to -10 to -14 C. Thaws may occur a few times per winter, but temperatures only barely rise above 0 C, and many winters lack above-freezing temperatures altogether. Cold snaps also occur with daytime temperatures below -10 C on 20 days, often even -15 C, and nights pushing -20 C or lower on 10 days. Snow cover lasts from the second half of November to the beginning of April. Sea ice formation begins in late November. Ice roads to Öland usually open by mid-January, and depending on wind patterns occasionally also to Latvia, though this is closely monitored due to the unstable nature of sea ice. The closure of these usually happens during the second half of March. Gotland's isolated location makes transportation to and from the mainland an issue from mid-December as ice breakers can no longer sustain shipping lanes. This makes the island reliant on cargo planes. This issue then recurs in spring. Ice breakup occurs in the first half of April.

Spring and fall are rather short transitional seasons, with variable weather conditions. Spring begins in early April, and is subject to at times extreme and sudden swings in temperature and weather, as is typical with Swedish aprilväder. Its arrival and progression are delayed by surrounding sea ice and cold water, with summer conditions not fully setting in until mid-June. Fog occasionally occurs along the coast in spring as well due to the cold sea water, leading to far lower temperatures in locations shrowded in fog while locations only a short distance inland may have sunshine and 15 C. Nature begins to blossom out in early-to-mid May, with meteorological summer arriving in mid-May. Fall arrives in early October, with fall foliage typically being observed from late September to late October. Compared to spring, fall sees a more steady decrease in temperatures, though sudden cold snaps may still happen in some years. Winter usually arrives in mid-November.

The highest recorded temperature in Visby was 36.7 C on July 25, 2018, which occurred during the hottest month on record, which had a mean temperature of 25.9 C. That July, 18 consecutive days featured highs above 30 C, from July 16 to August 1, and the highest recorded daily minimum of 26.6 C happened on July 26. The coldest recorded temperature was -37.4 C on February 4, 1966, while the lowest daily maximum was -33.2 C on January 12, 1987. The coldest month was January 1987, with a mean of -20.8 C. The longest streak of sub-zero temperatures was 159 days from November 3, 1941, to April 10, 1942.

Annual precipitation amounts to only 415 mm, making Visby one of Sweden's driest cities. This, combined with Gotland's karstic geology makes meltwater reservoirs crucial to water supply, especially during prolonged summer droughts, which are not uncommon. Snowfall amounts to 148 cm, largely concentrated from November to March, but heavy snowfall has occurred in both October and April. Extreme ocean-effect snowstorms have occurred in Visby, though not quite as severe as the snow totals seen on the east coast of Gotland. Still, the snowiest day on record, November 6, 1965, saw 175 cm accumulate, when Fårö received a whopping 325 cm. This was one of the main reasons that 1965-1966 became the snowiest season on record with a total of 403 cm. Typically, snow depth peaks at around 80 cm in mid-March, before the spring thaw, with a record depth set at 301 cm on March 16, 1966. The longest continuous snow cover lasted 190 days from October 24, 1941 to May 1, 1942.

Visby enjoys one of the sunniest climates in Sweden, with around 2500 hours of sunshine per year, a major contributor to the island's tourism industry.

Seasonal averages:

Temperature change across the seasons.

Gulf stream collapse
Frankfurt has a humid continental climate (Dfa) according to the Köppen climate classification. Owing to its location in the Upper Rhine Valley, it ranks among Germany's hottest cities, along with Freiburg and Karlsruhe. Summers are hot and humid, with average highs of around 27 to 30 C. Nights in the suburbs and outskirts of the city offer some relief from daytime heat, with temperatures between 16 and 18 C, though lower in the Taunus mountains and higher in the downtown area. Heatwaves occur every summer, and can at times be severe, as temperatures soar to around 40 C. Nights during such conditions provide little relief, as tropical nights are the norm with lows above 20 C, averaging 32 such instances a year. In downtown Frankfurt, these conditions are exacerbated due to the urban heat island effect, and the inner city is plagued by nighttime lows as much as 5°C higher than its surroundings. Some locals take up residence in the mountains to escape the heat. Powerful thunderstorms often mark the end of such heatwaves, which, if coupled with drought conditions, can lead to flash flooding. Still, cooler days with highs of 20 to 25 C occur from time to time, with lows falling into the lower teens °C (50s °F). Sunshine is then often mixed with passing showers that produce most non-thunderstorm summer rainfall. On average, there are 104 days with highs at or above 25 C and 37 above 30 C. There are typically 1-3 days when the mercury reaches 40 C. Overall, highs generally remain above 20 C from early May to late September.

Winters are cold and snowy. Though relatively mild by German standards, Frankfurt's inland position still renders it colder than the Ruhr. Daytime highs remain below 0 C for an average of 82 days, and generally do so from early December to mid-February. Typical conditions see highs hover around -1 to -3 C, with nights falling to -7 to -11 C. Thaws occur from time to time when intrusions of mild, Atlantic air move in from France, but such spells are usually brief, lasting only a few days. Cold snaps also occur with daytime temperatures below -10 C on 4 days and nights pushing -20 C or lower on 5 days. Still, these are usually fairly brief when compared to locations in Bavaria or former East Germany. Snow cover typically settles by mid-December, sticking until early March. The Main usually freezes over in early December, allowing for ice skating during the Christmas holidays. It begins to break up in early March. Spring flooding occasionally occurs, but thanks to the Main's smaller volume, such floods are nowhere near as severe as those along the Rhine.

Spring and fall are fairly short transitional seasons, though tend to feature relatively stable weather conditions. Frankfurt is among the first German cities to welcome spring in the first half of March, and, unlike large portions of northern Germany, spring cold snaps are rare. Starting in late February, temperatures steadily rise, and nature blossoms out in early April. Meteorological summer arrives in late April, though true summer conditions typically wait until mid-May. Summer conditions linger through September into early October, with fall arriving in mid-October. Fall foliage can typically be observed from the second week of October to early November. Frankfurt often sees Indian summers, with brief returns of summer-like warmth possible through the end of October. Compared to spring, fall can often see a much more rapid decline in temperature, as the first snowfall is seen in early November, with winter arriving by late November.

The highest recorded temperature in Frankfurt was 43.2 C on July 29, 2012. The hottest month on record was the following August, which had a mean temperature of 27.6 C. That month, 8 consecutive days featured highs above 40 C, August 5-13, and the highest recorded daily minimum of 29.1 C happened on August 20. The coldest recorded temperature was -31.6 C on January 8, 1942, while the lowest daily maximum was -23.2 C on January 12, 1987. The coldest month was January 1987, with a mean of -13.8 C. The longest streak of sub-zero temperatures was 111 days from November 16, 1941, to March 6, 1942.

Annual precipitation amounts to 502.7 mm, a fairly low amount by German standards. While the Main usually supplies a surplus of water to the region, extended droughts can put stress on both regional agriculture and trade as river levels drop. Snowfall amounts to 108 cm, largely concentrated from November to February, but heavy snowfalls occasionally occur in March as well. Snow in October and April is rare, and amounts are very limited. The snowiest day on record, February 3, 1979, saw 76 cm accumulate, impeding traffic for weeks in some mountainside locations. This was one of the main reasons that 1978-79 became the snowiest season on record with a total of 203 cm. Typically, snow cover peaks at around 40 cm in mid-February, before the spring thaw, with a record depth set at 121 cm on February 16, 1997. The longest continuous snow cover lasted 143 days from November 10, 1924 to April 1, 1925.

Seasonal averages:

Temperature change across the seasons.