Cooler-than-normal temperatures and rain are in the forecast for Ottawa this Saturday as runners prepare to participate in the Tamarack Ottawa Race Weekend. Environment Canada calls for a high of 13 C and a 70 per cent chance of showers today. A low of 7 C, partly cloudy skies and a 40 per cent chance of showers are expected for tonight. On Sunday, a high of 18 C, a mix of sun and cloud, a 40 per cent chance of showers and a risk of thunderstorms are anticipated. A low of 10 C and cloudy periods are in the forecast overnight. On Monday, a high of 22 C, a mix of sun and cloud, a 40 per cent chance of showers and a risk of thunderstorms are expected. A low of 11 C and cloudy periods are expected for the night. The average temperatures for this time of year are a high of 21 C and a low of 10 C.