Recent international evidence shows that in many stock markets, general index returns are significantly higher during winter months than during summer months. We study the interaction between this anomaly - known as the Halloween effect - and the January effect and other well-known anomalous findings on portfolios formed on Size, Dividend Yield, Book to Market ratios, Earnings Price ratios and Cash Flow Price ratios in equally but also value weighted portfolios for the US market. Our main findings are that contrary to the January effect, the Halloween effect seems a market wide phenomenon unrelated to these well-known anomalies. All portfolios in our study show higher average winter returns than summer returns. In most portfolios this difference is statistically and economically significant. We confirm recent results which suggest that the January effect plays an important role not only in explaining the small firm effect but also - together with size - in explaining the Book to Market ratio anomaly. In addition, we find in a similar fashion that controlling for the January effect and using value weighted portfolio returns substantially reduces the Earnings to Price, Cash Flow to Price and Dividend Yield effects.