"The Earth’s atmosphere plays host to numerous weather phenomena that affect life and shape the planet. Understanding these phenomena requires knowledge of the interaction between temperature and humidity. Temperature affects humidity, which in turn affects the potential for precipitation. The interaction of temperature and humidity also directly affects the health and well-being of humans. Relative humidity and dew point, values commonly used by meteorologists, give the means to understand this interaction" .
Relative Humidity 
Relative humidity is given as a percentage. This percentage tells you how close the air is to being saturated. If the relative humidity is 100%, the air is saturated. If the relative humidity is 50%, the air contains half the water vapour required for it to be saturated. If the amount of water vapour in the air increases, the relative humidity increases, and if the amount of water vapour in the air decreases, the relative humidity decreases.
However, relative humidity is dependent on air temperature, too. If the water vapour content stays the same and the temperature drops, the relative humidity increases. If the water vapour content stays the same and the temperature rises, the relative humidity decreases. This is because colder air doesn't require as much moisture to become saturated as warmer air.
Dew Point 
Dew point is a better indicator of humidity than relative humidity because it is not a percentage dependent on temperature. The dew point is the temperature to which the air would have to be cooled to become saturated. Below the dew point, water will condense out of the air onto surfaces. In the early morning, grass surfaces will be coated with water if the night-time temperature has dropped below the dew point. When humidity is high, the dew point temperature is only a few degrees below, or equal to, air temperature. In dry places, like deserts of the south-west, air temperature can be 50 or 60 degrees above the dew point. Generally dew point is a more reliable indicator of humidity than relative humidity because dew point is not changed by a change in air temperature and doesn't fluctuate much throughout the day.
Effects on human health and comfort
Temperature and humidity affect people’s comfort levels as well as their health. High humidity and heat means more water in the air, which can carry odour molecules further, leading to considerable stench in summer around bacteria sources such as garbage. Recent studies reveal connections between humidity, temperature and public health. Temperature and humidity directly influence influenza virus transmission in temperate regions of the world. Influenza activity increases in winter in each hemisphere's temperate zones. Flu virus thrives when outdoor temperatures grow colder. While winter relative humidity is higher in winter, indoor relative humidity is much drier due to heating. The exposure to cold outside air and dry inside air increases flu virus transmission. Research indicates aerosolized influenza virus is more stable at lower relative humidity. The half-life of the virus drops at higher temperatures and cannot be spread as easily .
Cardiac risks also result from changes in temperature and humidity. Researchers found that a joint effect exists between temperature and humidity on cardiovascular disease mortality. In conditions of low temperatures and high humidity, cardiovascular death rates increased. This could be due to high humidity affecting thrombotic risk, combined with the human body’s various cold-stress responses.
Tricky relationship to be aware of
Although we've used scientific articles to help you understand how the humidity and temperature affects your well-being, you should keep in mind one important information: There is no unique relationship between temperature and humidity. However humidity can change a person’s comfort at the same temperature as humans are sensitive to the water vapor content in the atmosphere.
I'll give you an example : If the air temperature is 24 °C (75 °F) and the relative humidity is zero percent, then the air temperature feels like 21 °C (69 °F). If the relative humidity is 100 percent at the same air temperature, then it feels like 27 °C (80 °F). In other words, if the air is 24 °C (75 °F) and contains saturated water vapour, then the human body cools itself at the same rate as it would if it were 27 °C (80 °F) and dry. Simply said, human body experiences greater distress of waste heat burden at high humidity than at lower humidity, given equal temperatures.
In cold climates, the outdoors temperature causes lower capacity for water vapor to flow about. Thus although it may be snowing and at high humidity relative to its temperature outdoors, once that air comes into a building and heats up, its new relative humidity is very low, making the air very dry, which causes discomfort.