Very Wet and Rather Cool
Temperatures
The average maximum temperature during June 2021 in Shoreham was 20.7 Celsius (69F), and that was about 1 Celsius (<2F) below normal for the time of year. The average minimum temperature was 13.0 Celsius (55F), and that was around the June average.
The highest temperature recorded during the month was 27.0 Celsius (81F), on the 16th, but only 2 other days, the 1st and 2nd, had maxima above 25 Celsius (77F). There were a few more pleasantly warm days, especially around mid-month, but in total there were only 18 days with maxima above 20 Celsius (68F), and only 7 of those days had highs above 23 Celsius (73F). A few very cool days occurred, but of the 12 days with maxima below 20 Celsius (68F), only 4 had values below 17 Celsius (63F). The 4th had a maximum of 15.8 Celsius (60F), with the other 3 very cool days positioned between the 19th and 22nd. The coolest day was the 21st with a high of 14.3 Celsius (58F).
There were no particularly warm nights during June, although on 7 occasions the temperature stayed above 15 Celsius (59F). The warmest nights mainly occurred during the third week, and on 3 out of the last 4 nights of the month. Only 3 of these warmer nights had minima above 16 Celsius (61F), the 15th, 17th and 18th had lows of 16.5 Celsius (62F), 17.3 Celsius (63F) and 16.4 Celsius (62F) respectively. The coolest nights occurred at the beginning of the second week and during the last week of June. On 5 nights the temperature dipped below 10 Celsius (50F), and on 2 of these cool nights, minima were below 9 Celsius (48F). On the 23rd a low of 8.9 Celsius (48F) was recorded with 8.8 Celsius (48F) occurring on the 26th.
The sea temperature rose steadily from 14 Celsius (57F) at the beginning of June, to 17 or 18 Celsius (63-64F) around mid-month, but then stayed around 16 or 17 Celsius (61-63F) for the remainder of the month.
Frost
No air frost occurred during June The lowest grass temperature occurred on the 26th when 7.2 Celsius (45F) was recorded.
Rain
Rainfall in June amounted to 102.8 millimetres (4 ins.) which was well over double the average for the month. It was the wettest June in the area for 9 years. Measurable rain fell on 13 days, which is 3 days above the average, and wet days (when 1 millimetre (0.04 ins.) or more of rain falls) numbered 11 days, and that was 5 days above the average. The first measurable rain of the month fell on the 3rd, but most of the 3.4 millimetres (0.1 in.) that fell during the ‘rain day’ (0900-0900 UTC) occurred on the morning of the 4th. The rain continued into the afternoon, adding another 7 millimetres (0.3 ins.) to the monthly total. It was dry between the 5th and 15th, but the 16th was the wettest day of the month with 20.6 millimetres (0.8 ins.) recorded. It was the beginning of an unsettled spell of weather that lasted until the 30th. Although 3 days, the 22nd, 23rd and 26th were dry, on other days rain was occasionally heavy. Daily totals included 18.2 millimetres (0.75 ins.) on the 17th, 9.4 millimetres (0.35 ins.) on the 18th, 15.2 millimetres (0.6 ins.) on the 21st and 9.8 millimetres (0.4 ins.) on the 29th.
Hail
No hail was observed in this part of Shoreham.
Thunder
Two separate thunderstorms occurred on the evening of the 16th, although the thunder was mostly quite distant. On the late afternoon of the 28th, there was a distant rumble from a storm to the north of the Downs.
Snow
No sleet or snow was observed this month in Shoreham.
Wind
Even though the month was wet, pressure was relatively high during June, with anticyclones generally positioned to the west or south of the country. That led to a predominance of winds blowing from between southwest and northwest. On days when the wind was generally indeterminate, afternoon sea breezes developed, and these mainly blew from the southwest. Overall, winds were lighter than normal. At Shoreham Airport, the highest gust recorded during the month was 28 knots (32 mph) from the north-northeast on the afternoon of the 21st.
Fog
There was fog on the morning of the 7th which lifted into low cloud by early afternoon, Several other days had low cloud and misty conditions overnight and during the mornings.
Statistics for June 2021
| Reporting Site | Highest Temp | Lowest Temp | Rain Total (mm) | Wettest | Rain days |
| Shoreham A/P | 23.8 | 6.5 | 69 | 15 | 13 |
| Thorney Island | 25.6 | 7.6 | 103 | 29 | 10 |
| Gatwick A/P | 28.4 | 5.5 | 84 | 25 | 12 |
| Herstmonceux | 27.7 | 7.5 | 113 | 37 | 14 |
| Bournemouth (Hurn) | 27.0 | 5.0 | 85 | 18 | 10 |
| Middle Wallop | 26.7 | 6.2 | 81 | 38 | 9 |
| Dieppe | 28.4 | 8.7 | 89 | 15 | 25 |