Climate and Average Weather Year Round in Derby Australia

In Derby, the wet season is sweltering, oppressive, and overcast and the dry season is hot and mostly clear. Over the course of the year, the temperature typically varies from 62°F to 101°F and is rarely below 55°F or above 105°F.

Based on the beach/pool score, the best time of year to visit Derby for hot-weather activities is from mid September to mid November.

The hot season lasts for 2.4 months, from September 30 to December 10, with an average daily high temperature above 98°F. The hottest month of the year in Derby is November, with an average high of 100°F and low of 77°F.

The cool season lasts for 2.3 months, from May 26 to August 3, with an average daily high temperature below 89°F. The coldest month of the year in Derby is July, with an average low of 63°F and high of 87°F.

In Derby, the average percentage of the sky covered by clouds experiences extreme seasonal variation over the course of the year.

The clearer part of the year in Derby begins around April 10 and lasts for 7.5 months, ending around November 26.

The clearest month of the year in Derby is August, during which on average the sky is clear, mostly clear, or partly cloudy 74% of the time.

The cloudier part of the year begins around November 26 and lasts for 4.5 months, ending around April 10.

The cloudiest month of the year in Derby is February, during which on average the sky is overcast or mostly cloudy 81% of the time.

A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in Derby varies very significantly throughout the year.

The wetter season lasts 3.5 months, from December 6 to March 24, with a greater than 27% chance of a given day being a wet day. The month with the most wet days in Derby is February, with an average of 14.7 days with at least 0.04 inches of precipitation.

The drier season lasts 8.5 months, from March 24 to December 6. The month with the fewest wet days in Derby is August, with an average of 0.1 days with at least 0.04 inches of precipitation.

Among wet days, we distinguish between those that experience rain alone, snow alone, or a mixture of the two. The month with the most days of rain alone in Derby is February, with an average of 14.7 days. Based on this categorization, the most common form of precipitation throughout the year is rain alone, with a peak probability of 54% on January 26.

Rainfall

To show variation within the months and not just the monthly totals, we show the rainfall accumulated over a sliding 31-day period centered around each day of the year. Derby experiences extreme seasonal variation in monthly rainfall.

The rainy period of the year lasts for 6.7 months, from November 8 to May 31, with a sliding 31-day rainfall of at least 0.5 inches. The month with the most rain in Derby is February, with an average rainfall of 8.4 inches.

The rainless period of the year lasts for 5.3 months, from May 31 to November 8. The month with the least rain in Derby is August, with an average rainfall of 0.0 inches.

The length of the day in Derby varies over the course of the year. In 2024, the shortest day is June 21, with 11 hours, 6 minutes of daylight; the longest day is December 21, with 13 hours, 10 minutes of daylight.

The earliest sunrise is at 5:01 AM on November 25, and the latest sunrise is 1 hour, 15 minutes later at 6:16 AM on July 7. The earliest sunset is at 5:18 PM on June 3, and the latest sunset is 1 hour, 8 minutes later at 6:26 PM on January 20.

Daylight saving time (DST) is not observed in Derby during 2024.

The figure below presents a compact representation of key lunar data for 2024. The horizontal axis is the day, the vertical axis is the hour of the day, and the colored areas indicate when the moon is above the horizon. The vertical gray bars (new Moons) and blue bars (full Moons) indicate key Moon phases.

We base the humidity comfort level on the dew point, as it determines whether perspiration will evaporate from the skin, thereby cooling the body. Lower dew points feel drier and higher dew points feel more humid. Unlike temperature, which typically varies significantly between night and day, dew point tends to change more slowly, so while the temperature may drop at night, a muggy day is typically followed by a muggy night.

Derby experiences extreme seasonal variation in the perceived humidity.

The muggier period of the year lasts for 7.7 months, from September 21 to May 11, during which time the comfort level is muggy, oppressive, or miserable at least 26% of the time. The month with the most muggy days in Derby is January, with 30.6 days that are muggy or worse.

The month with the fewest muggy days in Derby is July, with 1.0 days that are muggy or worse.

This section discusses the wide-area hourly average wind vector (speed and direction) at 10 meters above the ground. The wind experienced at any given location is highly dependent on local topography and other factors, and instantaneous wind speed and direction vary more widely than hourly averages.

The average hourly wind speed in Derby experiences significant seasonal variation over the course of the year.

The windier part of the year lasts for 9.5 months, from May 12 to February 26, with average wind speeds of more than 8.0 miles per hour. The windiest month of the year in Derby is December, with an average hourly wind speed of 9.4 miles per hour.

The calmer time of year lasts for 2.6 months, from February 26 to May 12. The calmest month of the year in Derby is March, with an average hourly wind speed of 6.9 miles per hour.

The predominant average hourly wind direction in Derby varies throughout the year.

The wind is most often from the east for 5.0 months, from March 19 to August 20, with a peak percentage of 53% on June 10. The wind is most often from the south for 1.4 weeks, from August 20 to August 30, with a peak percentage of 33% on August 24. The wind is most often from the west for 6.6 months, from August 30 to March 19, with a peak percentage of 56% on January 1.

Derby is located near a large body of water (e.g., ocean, sea, or large lake). This section reports on the wide-area average surface temperature of that water.

The average water temperature experiences some seasonal variation over the course of the year.

The time of year with warmer water lasts for 5.8 months, from November 7 to April 30, with an average temperature above 85°F. The month of the year in Derby with the warmest water is March, with an average temperature of 87°F.

The time of year with cooler water lasts for 2.6 months, from June 23 to September 10, with an average temperature below 77°F. The month of the year in Derby with the coolest water is August, with an average temperature of 75°F.

To characterize how pleasant the weather is in Derby throughout the year, we compute two travel scores.

The tourism score favors clear, rainless days with perceived temperatures between 65°F and 80°F. Based on this score, the best time of year to visit Derby for general outdoor tourist activities is from early May to early October, with a peak score in the third week of August.

The beach/pool score favors clear, rainless days with perceived temperatures between 75°F and 90°F. Based on this score, the best time of year to visit Derby for hot-weather activities is from mid September to mid November, with a peak score in the first week of October.

Methodology

For each hour between 8:00 AM and 9:00 PM of each day in the analysis period (1980 to 2016), independent scores are computed for perceived temperature, cloud cover, and total precipitation. Those scores are combined into a single hourly composite score, which is then aggregated into days, averaged over all the years in the analysis period, and smoothed.

Our cloud cover score is 10 for fully clear skies, falling linearly to 9 for mostly clear skies, and to 1 for fully overcast skies.

Our precipitation score, which is based on the three-hour precipitation centered on the hour in question, is 10 for no precipitation, falling linearly to 9 for trace precipitation, and to 0 for 0.04 inches of precipitation or more.

Our tourism temperature score is 0 for perceived temperatures below 50°F, rising linearly to 9 for 65°F, to 10 for 75°F, falling linearly to 9 for 80°F, and to 1 for 90°F or hotter.

Our beach/pool temperature score is 0 for perceived temperatures below 65°F, rising linearly to 9 for 75°F, to 10 for 82°F, falling linearly to 9 for 90°F, and to 1 for 100°F or hotter.

Definitions of the growing season vary throughout the world, but for the purposes of this report, we define it as the longest continuous period of non-freezing temperatures (≥ 32°F) in the year (the calendar year in the Northern Hemisphere, or from July 1 until June 30 in the Southern Hemisphere).

Temperatures in Derby are sufficiently warm year round that it is not entirely meaningful to discuss the growing season in these terms. We nevertheless include the chart below as an illustration of the distribution of temperatures experienced throughout the year.

Growing degree days are a measure of yearly heat accumulation used to predict plant and animal development, and defined as the integral of warmth above a base temperature, discarding any excess above a maximum temperature. In this report, we use a base of 50°F and a cap of 86°F.

This section discusses the total daily incident shortwave solar energy reaching the surface of the ground over a wide area, taking full account of seasonal variations in the length of the day, the elevation of the Sun above the horizon, and absorption by clouds and other atmospheric constituents. Shortwave radiation includes visible light and ultraviolet radiation.

The average daily incident shortwave solar energy experiences some seasonal variation over the course of the year.

The brighter period of the year lasts for 2.1 months, from September 24 to November 27, with an average daily incident shortwave energy per square meter above 7.1 kWh. The brightest month of the year in Derby is October, with an average of 7.5 kWh.

The darker period of the year lasts for 2.6 months, from May 5 to July 25, with an average daily incident shortwave energy per square meter below 5.6 kWh. The darkest month of the year in Derby is June, with an average of 5.1 kWh.

For the purposes of this report, the geographical coordinates of Derby are -17.303 deg latitude, 123.629 deg longitude, and 43 ft elevation.

The topography within 2 miles of Derby is essentially flat, with a maximum elevation change of 89 feet and an average elevation above sea level of 23 feet. Within 10 miles is essentially flat (194 feet). Within 50 miles contains only modest variations in elevation (883 feet).

The area within 2 miles of Derby is covered by sparse vegetation (48%), shrubs (32%), and grassland (12%), within 10 miles by water (41%) and sparse vegetation (39%), and within 50 miles by sparse vegetation (64%) and water (20%).