Reading a Climate Table: A Quick Tutorial

Every city on HistoricalClimate.com has a monthly table with six columns: average high, average low, mean temperature, precipitation, snow, and sunny days. Here's how a meteorologist reads it.

Compare the average high and low within a single month. A wide gap (say, 40°F) means a continental climate with big day-night swings — think Denver. A narrow gap (12°F) means a marine climate — San Francisco again.

Compare the summer and winter rows. A big swing between January and July means a seasonal climate; a small swing means a moderate one. Honolulu is famously monotonous in this sense — temperatures barely move.

Precipitation in inches tells you volume, but the sunny-days column tells you pattern. High precip with high sunny-days means concentrated storms; high precip with low sunny-days means overcast drizzle.