In viscosity measurement, temperature control is very important. In this research, the effects of temperature distribution in viscosity measurement are investigated. Vibrational viscometers are preferred in experiments over other types of viscometers due to their low cost, easy to use and effective continuous viscosity measurement capability. This study was conducted in two parts. In the first part, thermal convection phenomenon within the experimental cup is analyzed. The experiments are carried out with three different standard fluids in continuously increasing temperature environment. Experimental outcomes show that when viscosity of the test fluid increases, the non-uniformity of the temperature field grows in the cup and results in viscosity measurement errors. In the second part, thermal conduction phenomenon is investigated. This experiment is repeated several times with different heating speeds in one selected standard fluid to gain a better understanding about the effect of thermal conduction in fluid viscosity. Experimental outcomes show that under some conditions viscosity measurement errors could reach up to 49.6 %. These findings have also been verified by mathematical calculations.