The study aimed at assessing farmers’ adaptations to rainfall related climate variability risks and their implications on food security in the semi-arid Sikonge District, Tanzania. Specifically the study aimed at characterizing the climate related rainfall and maize production risks; assessing the efficacy of adaptation strategies used by farmers; and assessing the adequacy of off-farm strategies used by farming households to sustain their food security in a changing climate. The study used both secondary and primary data. The secondary data were annual rainfall, rain days, area under maize production and maize yields data; and the primary data were on adaptation and coping strategies adopted by farm families to remain food secure in a changing climate and other off-farm income generating activities done by farmers in the study area. The secondary data were collected from Tanzania Meteorological Agency (TMA) for rainfall data and the Ministry of Agriculture, Food security and Cooperatives for maize production data. The primary data were collected from 120 households using a structured questionnaire. Auto-Regressive Integrated Moving Average (ARIMA) approach was used to analyse the relationship between maize production, annual rainfall and number of rain days for the past 30 years. Analysis of efficacy of farmers’ adaptation strategies on household food security was done by using descriptive statistics. The findings show a significant (P<0.001) positive relationship between maize yields and the climatic factors entailing rain days and rainfall amount. This suggests the likely impact of rainfall related climate change and variability on maize production. The findings show that farmers responded to the climate change and variability by adopting different adaptation and coping strategies, popular ones being sale of livestock and growing drought tolerant, high yielding and early maturing crop varieties. Most of the adaptation strategies adopted by farmers were those related to decreasing household vulnerability both in short-run and long-run. Off-farm activities were significant contributors of household food security. Income generated from off-farm activities enabled most households to supplement their food needs hence graduated from food insecurity.