Analysis of Temperature and Rainfall Trends from 1994 to 2024 in Kiminini Sub-County, Trans Nzoia County, Kenya

Abstract

Climate variability and climate change have increasingly affected agricultural productivity and rural livelihoods in Kenya, particularly in areas dependent on rain-fed agriculture. This study analyzed temperature and rainfall trends from 1994 to 2024 in Kiminini Sub-County, Trans Nzoia County. The study aimed to examine long-term changes in annual temperature and rainfall patterns and determine their implications for agricultural activities within the study area. A descriptive research design employing quantitative trend analysis methods was adopted. Secondary climatic data on annual rainfall totals and average annual temperatures were obtained from meteorological records, county agricultural reports, and climate databases. Data were analysed using descriptive statistics, linear regression analysis, graphical trend analysis, and the Mann–Kendall trend test. The findings revealed that average annual temperatures in Kiminini Sub-County increased steadily over the thirty-year study period at an estimated rate of approximately 0.05°C per year, indicating a significant warming trend. Rainfall patterns exhibited high interannual variability characterized by fluctuating annual totals, delayed onset of rainfall seasons, prolonged dry spells, and occasional extreme rainfall events. The Mann–Kendall test results showed a statistically significant increasing trend in annual temperature (Z = 2.84, p < 0.05), leading to rejection of the null hypothesis that no temperature trend existed between 1994 and 2024. Conversely, rainfall trends showed a weak declining and statistically insignificant pattern (Z = -1.21, p > 0.05), indicating that annual rainfall variability was high but lacked a strong monotonic trend over the study period. The study further established that increasing temperatures and irregular rainfall patterns negatively affected agricultural productivity through reduced soil moisture availability, increased crop stress, declining maize and wheat yields, and disruption of planting calendars among farmers. The study concluded that climate variability has intensified in Kiminini Sub-County and continues to threaten sustainable agricultural production and food security. The study recommends adoption of climate-smart agricultural practices, improved dissemination of climate information services, investment in irrigation and water conservation technologies, and strengthening of local climate adaptation strategies. The findings provide useful information for policymakers, researchers, agricultural extension officers, and farmers in developing effective climate resilience interventions within the study area.