The 30-year period of averages currently in use by the Meteorological Office is 1981 to 2010.
All data is recorded using standard Meteorological Office equipment, thermometers that are tested and certified, rain gauges and sun recorders, set on a standard site inspected by the meteorological office. On any one day the temperature, rainfall and sunshine in different parts of the Borough can vary greatly, readings are often queried by people using untested and improperly installed equipment.
The temperatures below are the monthly averages, specific daily data can be found on the What was it like page.
The Met Office divides the year up into precise 3 monthly periods:
|January||Rainfall mm||Sunshine Hrs.||Maximum oC||Minimum oC||Notes|
|30 year average||75.9||67.2||8.6||4.0||Minimum temperatures remained above freezing on all days except the 31st .The greatest rainfall was 10.1 mm on Sunday 29th. Rain fell on 10 days, Hail 25th.|
|February||Rainfall mm||Sunshine Hrs.||Maximum oC||Minimum oC||Notes|
|30 year average||64.3||79.9||8.3||3.1||Minimum air temperatures remained low, falling below freezing on 11 days, lowest ground temperature minus 8.4 degrees on Sunday 12th.|
End of winter: Rainfall 133.8mm, 60% of the 30-year average, Sunshine 102.4% of the 30-year average. Due to warm December and January average temperatures were above the seasonal average.
|March||Rainfall mm||Sunshine Hrs.||Maximum oC||Minimum oC||Notes|
|30 year average||61.8||128.7||10.3||4.7||Warm, sunny and dry, all temperatures well above average with sunshine in line with summer months. Thick fog was predominant on the 1st 13th and 15th|
|April||Rainfall mm||Sunshine Hrs.||Maximum oC||Minimum oC||Notes|
|30 year average||49.4||196.3||12.5||5.7||Wettest April since 1880, 320 % of the average rainfall was recorded mainly in the second half, two days each recorded over 25 mm or 1 inch of rain, and the rainfall from 23rd to 25th inclusive equalled the normal April average. Hail 4th and 14th.|
|May||Rainfall mm||Sunshine Hrs.||Maximum oC||Minimum oC||Notes|
|30 year average||46.4||223.6||15.5||8.8||Friday 25th sweltered in 25.3 degrees, which made it the warmest Weymouth day in the month of May since 1947. Thick fog 9th and 10th|
End of Spring: Maximum and minimum temperatures above average, sunshine 118% and rainfall 135% of average.
|June||Rainfall mm||Sunshine Hrs.||Maximum oC||Minimum oC||Notes|
|30 year average||45.3||225.3||18.0||11.0||Wettest June, exceeding the 1980 total by 13.6mm. Sunshine avoided the low record set in 1997 by 3 hours 36 minutes. Thick fog was predominant on the 26th and 27th .|
|July||Rainfall mm||Sunshine Hrs.||Maximum oC||Minimum oC||Notes|
|30 year average||37.1||239.2||20.2||13.0||Second wettest since 1880, first week saw 308% of the July average rainfall. Fog Wednesday 4th.|
|August||Rainfall mm||Sunshine Hrs.||Maximum oC||Minimum oC||Notes|
|30 year average||47.8||219.6||20.3||13.8||Wettest since 1997, Thunder and lightning 0830 on 18th thunder also 1040 on Friday 26th.|
End of Summer: Sunshine 4% down whilst rainfall 41% above average, minimum temperatures well above average but maximum temperatures slightly below average.
|September||Rainfall mm||Sunshine Hrs.||Maximum oC||Minimum oC||Notes|
|30 year average||56.4||171.6||18.5||12.2||Very dry first 3 weeks with plenty of sunshine, followed by an extremely wet week making it the wettest September since 1999.|
|October||Rainfall mm||Sunshine Hrs.||Maximum oC||Minimum oC||Notes|
|30 year average||85.1||123.9||15.2||9.9||45% above average rainfall, poor month for sunshine, 2 occasions of ground frost.|
|November||Rainfall mm||Sunshine Hrs.||Maximum oC||Minimum oC||Notes|
|30 year average||93.1||85.8||11.9||6.8||45% above average rainfall, poor month for sunshine, 2 occasions of ground frost.|
End of Autumn: Sunshine Average, Rainfall up by 67%, temperatures just below average.
|December||Rainfall mm||Sunshine Hrs.||Maximum oC||Minimum oC||Notes|
|30 year average||88.6||63.6||9.1||4.3||A very wet month wettest since 1989, and as with last year one of the warmest Decembers on record, with above average sunshine. 1 air frost, but 11 ground frosts very windy.|
The average annual sunshine is 1855 hours 18 minutes, 2012 saw a decrease in sunshine in a year that was pretty bad all over the country recording just 1768 hours and 24 minutes, the sunniest day was 24th July with 14 hours and 42 minutes.
At the beginning of the year Water Boards were concerned with the lack of rainfall, their fears were about to be reversed; the average annual rainfall in Weymouth is 744.8 millimetres, 2012 almost doubled this to 1133.5 mm, 611.3 mm above the 30-year average. January, February, March and May were all drier than average whilst all other months have exceeded the monthly average. April, June and July each trebled the average, making this the wettest year since 1960 and the second wettest since 1880. However during the Olympic Games there was a respite in the weather much to everybody’s relief.
The prevailing wind for Weymouth is from the southwest, 135 days the wind came from the southwest quadrant, 49 days came from the southeast quarter, 98 from the northeast direction, 82 from the northwest and 2 days were calm at the 0900 observation. Gale force winds, i.e. wind at a speed of 34 knots or more, for a period of 10 minutes, or for gust exceeding 43 knots occurred on 29 occasions, gusts occurred more frequently but not for extended periods. The highest being 57 knots on 3rd January.
The months at the ends of the years were all above the average temperature and the summer months cooler than average. The warmest day was 27th July at 25.5 oC.
All months except February were above the 30-year average, the highest minimum temperature was on 27th July at 18.5 oC
The air temperature dropped to zero or below on 12 days, most of these were in February. Lowest air temperature was -4.0oC on 3rd February.
Occurred on 49 occasions throughout the year, January 5 times, February 17 times, March 8 times, and April 4 times, 4 in November, and on 11 occasions during December, the lowest ground temperature was -8.4oC on 7th February.
The sea temperature is measured in Weymouth Bay from the Pleasure Pier, (and is mainly recorded for the convenience of the bathers, whether they be local or visitors), the temperature of the water in the bay varies considerably from day to day depending on tide and wind, the rate of cooling and warming is a lot slower that of the air temperature, and in the winter is often a lot warmer than the air temperature. The temperature is measured 1 metre below the surface. The sea temperature was mainly above the 30-year average, and 12th August raised the mercury to 17.2 the highest recorded.
No occurrences of thunder were recorded.under was only noted 7 times once in January, 3 times in May, once in June and on 3 occasions in August.
Hail was recorded 4 times once each in January and December and twice during April.
Snow, a rare phenomenon in Weymouth was even rarer and did not fall in 2012.
Fog is 'wet air', not to be confused with haze, which is 'dirty but dry air'. When assessing visibility, fog reduces visibility to 1000 metres, whilst thick fog brings visibility down to 400 metres. Fog was observed on 11 occasions at the morning observation. Mist and haze was present on several occasions during the year.