Joseph Isangura
Tanzania is entering a period marked by shifting and intensifying rainfall patterns as December progresses, with weather experts noting that global pressure systems are continuing to influence how rain is distributed across the country.
A review of the first ten days of the month shows that atmospheric conditions in both hemispheres have been changing in ways that directly affect local weather.
During the early part of December, major pressure systems in the northern hemisphere—particularly those associated with the Azores and Siberia—strengthened noticeably. Meanwhile, the corresponding systems in the southern hemisphere, including the St. Helena and Mascarene highs, weakened. This contrast caused the Intertropical Convergence Zone to shift southward, positioning it above regions such as the Lake Victoria Basin, the western corridor and parts of the southern highlands.
This southward shift played a significant role in enhancing rainfall systems across those areas. Moisture-laden winds from the Indian Ocean also helped boost rainfall along coastal areas, especially during the latter half of the ten-day period. As a result, several regions—including the Lake Victoria zone, western districts and parts of the southwestern highlands—experienced periods of rain accompanied by thunderstorms. Northeastern highlands and the northern coast recorded scattered showers during the same period.
Looking ahead to December 11–20, meteorologists expect a continuation of the same trend. The strengthening of northern hemisphere pressure systems and the weakening of those in the south are likely to keep the Intertropical Convergence Zone positioned over the Lake Victoria Basin, western regions, central Tanzania and the southern highlands. At the same time, moisture-driven winds from the ocean are expected to maintain rainfall activity along the coast.
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Forecasts indicate that the Lake Victoria Basin—including Kagera, Geita, Shinyanga, Mwanza, Simiyu and Mara—will likely continue to see rainfall, some of it accompanied by thunderstorms. The northeastern highlands of Arusha, Manyara and Kilimanjaro are expected to receive light to moderate showers. Along the northern coast, including Tanga, parts of Morogoro, Pwani, Dar es Salaam and the islands of Unguja and Pemba, scattered rainfall is expected, supported by continued moisture movement from the sea.
Western regions such as Kigoma, Katavi and Tabora may also see rainfall with isolated thunderstorms. Central Tanzania—particularly Dodoma and Singida—is forecast to receive scattered showers. The southern highlands, including Rukwa, Songwe, Mbeya, Njombe and Iringa, are expected to experience intermittent rainfall with thunder. Meanwhile, southern regions such as Mtwara, Lindi, Ruvuma and the southern parts of Morogoro will likely receive scattered rain during the forecast period.
Experts say the pattern reflects a familiar seasonal transition as the East Africa region moves deeper into the December rainfall phase. They note that close monitoring will continue, especially in areas that are more vulnerable to intense downpours, flash floods and strong winds.
Authorities are advising the public and local planners to remain attentive to updated forecasts, which continue to be released by national weather services such as the Tanzania Meteorological Authority.
