The consequences of climate change have been considerably high to smallholders in most of Sub-Saharan Africa. These impacts have been more enormous to crop production and other attached livelihoods. However, the comprehensive assessment of these impacts has suffered numerous challenges because crop productivity is also susceptible to other factors involved in the production process. This study aimed to understand how crop yields are affected by climate change in the semiarid zone of Tanzania. The findings would establish a thorough literature within smallholder adaptation in the area. Furthermore, they will intensify strategies to cope with reduced yields attributed by climate-change impacts. Outcomes: There has been a dramatic decrease in rainfall (R2 = 0.21) and increase in temperature (R2 = 0.30). In addition, we found that rainfall and temperature variability had positive (R2 ~ 0.5) and negative (R2 ~ 0.3) correlations with crop yields, respectively. Discussion: The decline in yields at both local and national levels elevated the magnitude of food shortage and poverty. The increasing climate impacts necessitate undertakings of various studies to plan, design, recommend, and implement various useful adaptation measures, especially in the vulnerable communities. Conclusion: To limit climate effects, we need to increase investments in adaptation and mitigation measures.