An outdoor degree ceremony is taking place tomorrow, 5 July, in the hot climate of Dubai. In recent years it has rained only 2 days in the four-month period June to September. However, the weather forecaster has predicted rain for tomorrow. When it actually rains, the weatherman correctly forecasts rain $85 \%$ of the time. When it doesn't rain, he incorrectly forecasts rain $15 \%$ of the time. Determine the probability that it will rain tomorrow.