John Wheeler: It is time for the annual summer dew point primer
When dew point temperatures reach into the 60s, the air feels distinctively humid.
FARGO — When dew point temperatures reach into the 60s, particularly the mid to upper 60s, the air feels distinctively humid. This is a feeling that does not happen in winter, even if the relative humidity is 100%. Relative humidity tells us how saturated the air is with respect to water vapor (humidity), whereas dew point is a direct guide to how the humidity in the air makes us feel.
Dew points in the 40s or lower do not feel humid, ever, even if it is foggy or raining. Dew points in the 50s reveal a hint of humidity, but not too much. When the dew point gets into the 60s, the air feels humid. Once the dew point reaches the 70s, the air is sticky and oppressive. On rare occasions, dew points in the 80s have occurred. Such weather is memorably and miserably muggy.