Monthly Climate Summary for  May  2009  at Hampstead

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A changeable month with a warm sunny finish

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Overall mean temperature was

13.2

ºC

which is

+1.3

degC

compared with the 1971-2000 average

Mean day maximum (09-21) was

17.6

ºC

Mean night minimum (21-09) was

8.8

ºC

Mean 24hr maximum (09-09) was

17.8

ºC

which is

+1.5

degC

compared with the 1971-2000 average

Mean 24hr minimum (09-09) was

8.7

ºC

which is

+1.1

degC

compared with the 1971-2000 average

Highest day max was

24.1

ºC

on  the

31

Lowest day max was

12.0

ºC

on  the

4

Highest night min was

14.2

ºC

on  the

29

Lowest night min was

3.9

ºC

on  the

4

Lowest grass min was

-1.1

ºC

on  the

4

Total rainfall this month was

30.6

mm

which is

51.8

per  cent

of the 1971-2000 average

Highest daily fall was

14.1

mm

on  the

25

Number of hours with rain was

36.0

hrs

Equiv. TSR rainfall duration was

25.2

hrs

which is

70.0

per  cent

of the 1971-2000 average

Highest no of wet hrs

10.0

hrs

on  the

25

Highest equiv duration

8.3

hrs

on  the

25

Mean rainfall intensity

1.21

mm/h

Total sunshine this month was

181.7

hrs

which is

100.9

per  cent

of the 1971-2000 average

Equiv. C/S sunshine total was

199.8

hrs

which is

100.9

per  cent

of the 1971-2000 average

Highest daily sun was

12.1

hrs

on  the

30

Maximum  snow depth  was

0.0

cm

on the

Mean sea-level pressure at 09Z

1019.3

mbar

which is

+4.1

mbar

compared with the 1961-1990 average

Highest pressure at 09Z

1033.5

mbar

on  the

29

Lowest  pressure at 09Z

1002.9

mbar

on  the

15

Number of days with:

Air Frost

0

0.2mm rain

13

No  sun

2

Snow lying

0

Grnd Frost

2

1.0mm

7

3h  sun

25

Snow/sleet

0

Max < 0ºC

0

5mm

1

6h  sun

14

Hail

0

Max > 10

31

10mm

1

9h  sun

7

Thunder

0

Max > 20

7

25mm

0

12h sun

2

Fog at 09Z

0

Max > 30

0

15h sun

0

Gale

0

Notable events during the month: