Weather2 on Twitter Weather2 on Facebook Weather2 on YouTube Weather2 blog

WEATHER FOR BUSINESS

We supply weather data to businesses

Free Weather Plugin

Add this forecast to your website



Local Weather

Gurnard 14 Day Long Range Forecast

14 Day weather providing an extended long range forecast outlook for Gurnard

Hampshire, United Kingdom

Long range weather outlook for Gurnard includes 14 day forecast summary:

The next 14 day outlook for Gurnard shows the average daytime maximum temperature will be around 12°C, with a high for the two weeks of 13°C expected on the afternoon of Friday 22nd. The mean minimum temperature will be 8°C, dipping to its lowest on the morning of Tuesday 26th at 6°C. The next 14 days will remain predominantly dry. On the whole winds are likely to be moderate.

DayLocal TimeDirSpeed/
Gust
Temp/
Feels Like
HumidityPressureCloud AmountPrecip AmountWeather
Wed 20
Mar
18:00

SW
SW

9 / 12 mph 53 / 49°F 92% 1033 mb
Low level cloud: 40%
Mid level cloud: 9%
High level cloud: 47%
Most Significant Cloud Type: low
48%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
21:00

WSW
WSW

8 / 10 mph 52 / 49°F 95% 1034 mb
Low level cloud: 57%
Mid level cloud: 5%
High level cloud: 26%
Most Significant Cloud Type: low
61%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
Thu 21
Mar
00:00

WSW
WSW

7 / 9 mph 51 / 48°F 94% 1034 mb
Low level cloud: 69%
Mid level cloud: 2%
High level cloud: 19%
Most Significant Cloud Type: low
71%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
03:00

WSW
WSW

6 / 9 mph 50 / 48°F 92% 1034 mb
Low level cloud: 89%
Mid level cloud: 1%
High level cloud: 18%
Most Significant Cloud Type: low
91%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
06:00

WSW
WSW

6 / 9 mph 50 / 47°F 88% 1034 mb
Low level cloud: 68%
Mid level cloud: 0%
High level cloud: 14%
Most Significant Cloud Type: low
69%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
09:00

W
W

6 / 10 mph 52 / 48°F 82% 1035 mb
Low level cloud: 68%
Mid level cloud: 0%
High level cloud: 7%
Most Significant Cloud Type: low
68%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
12:00

WSW
WSW

5 / 7 mph 54 / 52°F 82% 1035 mb
Low level cloud: 83%
Mid level cloud: 0%
High level cloud: 4%
Most Significant Cloud Type: low
83%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
15:00

SW
SW

5 / 7 mph 55 / 53°F 82% 1033 mb
Low level cloud: 56%
Mid level cloud: 0%
High level cloud: 4%
Most Significant Cloud Type: low
56%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
18:00

SW
SW

5 / 7 mph 55 / 53°F 88% 1032 mb
Low level cloud: 38%
Mid level cloud: 0%
High level cloud: 1%
Most Significant Cloud Type: low
38%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
21:00

SSW
SSW

4 / 6 mph 53 / 52°F 90% 1033 mb
Low level cloud: 49%
Mid level cloud: 0%
High level cloud: 0%
Most Significant Cloud Type: low
48%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
Fri 22
Mar
00:00

S
S

5 / 7 mph 51 / 50°F 88% 1032 mb
Low level cloud: 21%
Mid level cloud: 0%
High level cloud: 0%
Most Significant Cloud Type: low
20%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
03:00

SSW
SSW

7 / 9 mph 51 / 48°F 88% 1030 mb
Low level cloud: 4%
Mid level cloud: 1%
High level cloud: 0%
Most Significant Cloud Type: low
3%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
06:00

SSW
SSW

8 / 12 mph 49 / 46°F 89% 1029 mb
Low level cloud: 18%
Mid level cloud: 0%
High level cloud: 0%
Most Significant Cloud Type: low
18%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
09:00

SW
SW

9 / 13 mph 52 / 48°F 85% 1029 mb
Low level cloud: 18%
Mid level cloud: 2%
High level cloud: 0%
Most Significant Cloud Type: low
19%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
12:00

SW
SW

11 / 15 mph 55 / 51°F 81% 1029 mb
Low level cloud: 30%
Mid level cloud: 4%
High level cloud: 0%
Most Significant Cloud Type: low
31%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
15:00

WSW
WSW

12 / 15 mph 56 / 52°F 81% 1028 mb
Low level cloud: 32%
Mid level cloud: 3%
High level cloud: 0%
Most Significant Cloud Type: low
33%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
18:00

WSW
WSW

10 / 11 mph 56 / 53°F 87% 1028 mb
Low level cloud: 3%
Mid level cloud: 3%
High level cloud: 0%
Most Significant Cloud Type: low
4%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
21:00

WSW
WSW

8 / 10 mph 54 / 51°F 92% 1029 mb
Low level cloud: 18%
Mid level cloud: 3%
High level cloud: 0%
Most Significant Cloud Type: low
18%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
Sat 23
Mar
00:00

WNW
WNW

6 / 12 mph 48 / 45°F 93% 1029 mb
Low level cloud: 23%
Mid level cloud: 4%
High level cloud: 90%
Most Significant Cloud Type: low
34%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
03:00

N
N

5 / 9 mph 47 / 44°F 91% 1029 mb
Low level cloud: 20%
Mid level cloud: 5%
High level cloud: 3%
Most Significant Cloud Type: low
22%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
06:00

NNE
NNE

8 / 16 mph 45 / 40°F 92% 1030 mb
Low level cloud: 72%
Mid level cloud: 11%
High level cloud: 78%
Most Significant Cloud Type: low
85%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
09:00

ENE
ENE

9 / 16 mph 47 / 43°F 88% 1031 mb
Low level cloud: 91%
Mid level cloud: 22%
High level cloud: 100%
Most Significant Cloud Type: low
100%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
12:00

ENE
ENE

11 / 15 mph 50 / 46°F 89% 1031 mb
Low level cloud: 91%
Mid level cloud: 21%
High level cloud: 100%
Most Significant Cloud Type: low
100%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
15:00

ENE
ENE

14 / 16 mph 51 / 47°F 85% 1030 mb
Low level cloud: 90%
Mid level cloud: 12%
High level cloud: 100%
Most Significant Cloud Type: low
100%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
18:00

ENE
ENE

13 / 16 mph 51 / 46°F 82% 1030 mb
Low level cloud: 76%
Mid level cloud: 16%
High level cloud: 100%
Most Significant Cloud Type: low
93%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
21:00

ENE
ENE

13 / 15 mph 49 / 43°F 83% 1031 mb
Low level cloud: 29%
Mid level cloud: 17%
High level cloud: 21%
Most Significant Cloud Type: low
37%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
Sun 24
Mar
00:00

NE
NE

12 / 16 mph 46 / 40°F 83% 1030 mb
Low level cloud: 45%
Mid level cloud: 23%
High level cloud: 14%
Most Significant Cloud Type: low
54%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
03:00

NE
NE

13 / 17 mph 45 / 39°F 83% 1030 mb
Low level cloud: 70%
Mid level cloud: 45%
High level cloud: 33%
Most Significant Cloud Type: low
89%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
06:00

NE
NE

12 / 17 mph 45 / 39°F 83% 1030 mb
Low level cloud: 69%
Mid level cloud: 45%
High level cloud: 96%
Most Significant Cloud Type: low
96%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
09:00

NE
NE

10 / 13 mph 48 / 43°F 80% 1031 mb
Low level cloud: 74%
Mid level cloud: 44%
High level cloud: 73%
Most Significant Cloud Type: low
97%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
12:00

NE
NE

9 / 15 mph 50 / 46°F 68% 1031 mb
Low level cloud: 26%
Mid level cloud: 28%
High level cloud: 0%
Most Significant Cloud Type: low
35%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
15:00

N
N

7 / 13 mph 52 / 49°F 62% 1030 mb
Low level cloud: 1%
Mid level cloud: 10%
High level cloud: 1%
Most Significant Cloud Type: medium
13%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
18:00

N
N

10 / 18 mph 51 / 47°F 71% 1031 mb
Low level cloud: 17%
Mid level cloud: 0%
High level cloud: 1%
Most Significant Cloud Type: low
16%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
21:00

NNE
NNE

10 / 15 mph 49 / 45°F 74% 1033 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 0%
Most Significant Cloud Type: high
0%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
Mon 25
Mar
00:00

NNE
NNE

13 / 17 mph 47 / 41°F 67% 1034 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 14%
Most Significant Cloud Type: high
13%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
03:00

NNE
NNE

11 / 15 mph 45 / 39°F 73% 1033 mb
Low level cloud: 0%
Mid level cloud: 1%
High level cloud: 21%
Most Significant Cloud Type: high
21%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
06:00

N
N

12 / 16 mph 44 / 38°F 78% 1034 mb
Low level cloud: 0%
Mid level cloud: 3%
High level cloud: 94%
Most Significant Cloud Type: medium
6%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
09:00

N
N

14 / 17 mph 47 / 41°F 73% 1035 mb
Low level cloud: 0%
Mid level cloud: 4%
High level cloud: 7%
Most Significant Cloud Type: medium
4%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
12:00

NNE
NNE

10 / 17 mph 49 / 45°F 67% 1035 mb
Low level cloud: 2%
Mid level cloud: 3%
High level cloud: 2%
Most Significant Cloud Type: low
3%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
15:00

NNE
NNE

11 / 20 mph 51 / 46°F 64% 1034 mb
Low level cloud: 37%
Mid level cloud: 2%
High level cloud: 5%
Most Significant Cloud Type: low
38%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
18:00

NE
NE

12 / 21 mph 51 / 46°F 70% 1034 mb
Low level cloud: 1%
Mid level cloud: 4%
High level cloud: 8%
Most Significant Cloud Type: medium
6%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
21:00

NE
NE

15 / 20 mph 49 / 43°F 65% 1037 mb
Low level cloud: 0%
Mid level cloud: 4%
High level cloud: 6%
Most Significant Cloud Type: medium
4%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
Tue 26
Mar
00:00

ENE
ENE

15 / 19 mph 47 / 40°F 63% 1037 mb
Low level cloud: 0%
Mid level cloud: 3%
High level cloud: 4%
Most Significant Cloud Type: medium
3%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
03:00

ENE
ENE

14 / 17 mph 45 / 39°F 66% 1037 mb
Low level cloud: 0%
Mid level cloud: 1%
High level cloud: 21%
Most Significant Cloud Type: medium
2%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
06:00

ENE
ENE

12 / 15 mph 44 / 37°F 69% 1038 mb
Low level cloud: 0%
Mid level cloud: 1%
High level cloud: 9%
Most Significant Cloud Type: medium
1%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
09:00

ENE
ENE

13 / 16 mph 45 / 39°F 66% 1039 mb
Low level cloud: 0%
Mid level cloud: 3%
High level cloud: 0%
Most Significant Cloud Type: medium
2%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
12:00

E
E

10 / 16 mph 47 / 42°F 62% 1039 mb
Low level cloud: 1%
Mid level cloud: 4%
High level cloud: 0%
Most Significant Cloud Type: medium
7%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
15:00

ESE
ESE

8 / 14 mph 48 / 44°F 64% 1038 mb
Low level cloud: 14%
Mid level cloud: 3%
High level cloud: 0%
Most Significant Cloud Type: low
15%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
18:00

SE
SE

6 / 11 mph 48 / 45°F 71% 1038 mb
Low level cloud: 1%
Mid level cloud: 1%
High level cloud: 5%
Most Significant Cloud Type: high
5%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
21:00

ESE
ESE

6 / 10 mph 46 / 44°F 77% 1039 mb
Low level cloud: 1%
Mid level cloud: 0%
High level cloud: 3%
Most Significant Cloud Type: high
3%
Expect 0.00 In of precipitation over the past 3 hours.
0.00 In
DayLocal TimeDirSpeed/
Gust
Temp/
Feels Like
HumidityPressureCloud AmountPrecip AmountWeather
Wed 27
Mar
00:00

ENE
ENE

14 / 23 mph 48 / 43°F 83% 1034 mb
Low level cloud: 16%
Mid level cloud: 0%
High level cloud: 2%
Most Significant Cloud Type: low
16%
0.00 In
06:00

ENE
ENE

13 / 20 mph 45 / 39°F 83% 1036 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 0%
Most Significant Cloud Type: high
0%
0.00 In
12:00

E
E

11 / 14 mph 53 / 49°F 70% 1040 mb
Low level cloud: 4%
Mid level cloud: 0%
High level cloud: 0%
Most Significant Cloud Type: low
4%
0.00 In
18:00

E
E

15 / 19 mph 49 / 44°F 62% 1037 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 0%
Most Significant Cloud Type: high
0%
0.00 In
Thu 28
Mar
00:00

ENE
ENE

5 / 6 mph 57 / 56°F 82% 1040 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 0%
Most Significant Cloud Type: high
0%
0.00 In
06:00

NNE
NNE

7 / 9 mph 48 / 45°F 87% 1043 mb
Low level cloud: 5%
Mid level cloud: 8%
High level cloud: 1%
Most Significant Cloud Type: low
7%
0.00 In
12:00

NNE
NNE

3 / 3 mph 58 / 58°F 69% 1040 mb
Low level cloud: 3%
Mid level cloud: 3%
High level cloud: 16%
Most Significant Cloud Type: low
5%
0.00 In
18:00

SSW
SSW

4 / 5 mph 58 / 58°F 81% 1037 mb
Low level cloud: 34%
Mid level cloud: 0%
High level cloud: 0%
Most Significant Cloud Type: low
34%
0.00 In
Fri 29
Mar
00:00

NNE
NNE

9 / 11 mph 51 / 47°F 87% 1039 mb
Low level cloud: 7%
Mid level cloud: 0%
High level cloud: 0%
Most Significant Cloud Type: low
7%
0.00 In
06:00

NNE
NNE

6 / 7 mph 51 / 49°F 87% 1037 mb
Low level cloud: 1%
Mid level cloud: 0%
High level cloud: 4%
Most Significant Cloud Type: high
3%
0.00 In
12:00

ESE
ESE

2 / 2 mph 58 / 59°F 74% 1037 mb
Low level cloud: 31%
Mid level cloud: 0%
High level cloud: 83%
Most Significant Cloud Type: low
41%
0.00 In
18:00

S
S

4 / 4 mph 61 / 61°F 83% 1034 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 1%
Most Significant Cloud Type: high
0%
0.00 In
Sat 30
Mar
00:00

N
N

2 / 2 mph 56 / 58°F 86% 1030 mb
Low level cloud: 26%
Mid level cloud: 20%
High level cloud: 100%
Most Significant Cloud Type: low
45%
0.00 In
06:00

E
E

10 / 15 mph 48 / 44°F 89% 1031 mb
Low level cloud: 11%
Mid level cloud: 0%
High level cloud: 4%
Most Significant Cloud Type: low
11%
0.00 In
12:00

W
W

9 / 10 mph 59 / 59°F 71% 1020 mb
Low level cloud: 49%
Mid level cloud: 14%
High level cloud: 13%
Most Significant Cloud Type: low
55%
0.00 In
18:00

ESE
ESE

7 / 8 mph 58 / 57°F 80% 1025 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 18%
Most Significant Cloud Type: high
18%
0.00 In
Sun 31
Mar
00:00

WNW
WNW

15 / 24 mph 46 / 39°F 87% 1012 mb
Low level cloud: 62%
Mid level cloud: 43%
High level cloud: 37%
Most Significant Cloud Type: low
81%
0.02 In
06:00

N
N

8 / 12 mph 48 / 44°F 91% 1022 mb
Low level cloud: 4%
Mid level cloud: 21%
High level cloud: 4%
Most Significant Cloud Type: medium
33%
0.00 In
12:00

NW
NW

18 / 23 mph 44 / 37°F 59% 1014 mb
Low level cloud: 12%
Mid level cloud: 46%
High level cloud: 0%
Most Significant Cloud Type: medium
79%
0.04 In
18:00

NNW
NNW

10 / 15 mph 55 / 52°F 76% 1023 mb
Low level cloud: 1%
Mid level cloud: 17%
High level cloud: 34%
Most Significant Cloud Type: medium
21%
0.01 In
Mon 01
Apr
00:00

NW
NW

11 / 22 mph 34 / 26°F 74% 1019 mb
Low level cloud: 0%
Mid level cloud: 17%
High level cloud: 37%
Most Significant Cloud Type: medium
18%
0.03 In
06:00

N
N

11 / 15 mph 42 / 36°F 78% 1028 mb
Low level cloud: 0%
Mid level cloud: 10%
High level cloud: 52%
Most Significant Cloud Type: medium
12%
0.00 In
12:00

WSW
WSW

28 / 32 mph 51 / 44°F 83% 1008 mb
Low level cloud: 93%
Mid level cloud: 73%
High level cloud: 45%
Most Significant Cloud Type: low
100%
0.09 In
18:00

WNW
WNW

5 / 6 mph 57 / 57°F 66% 1027 mb
Low level cloud: 20%
Mid level cloud: 4%
High level cloud: 14%
Most Significant Cloud Type: low
22%
0.00 In
Tue 02
Apr
00:00

W
W

26 / 40 mph 50 / 43°F 88% 997 mb
Low level cloud: 69%
Mid level cloud: 60%
High level cloud: 75%
Most Significant Cloud Type: low
99%
0.19 In
06:00

S
S

9 / 11 mph 49 / 44°F 73% 1020 mb
Low level cloud: 0%
Mid level cloud: 70%
High level cloud: 79%
Most Significant Cloud Type: medium
73%
0.00 In
12:00

NW
NW

9 / 11 mph 50 / 46°F 68% 996 mb
Low level cloud: 63%
Mid level cloud: 10%
High level cloud: 21%
Most Significant Cloud Type: low
68%
0.17 In
18:00

SW
SW

20 / 23 mph 53 / 47°F 80% 1005 mb
Low level cloud: 60%
Mid level cloud: 4%
High level cloud: 33%
Most Significant Cloud Type: low
65%
0.00 In
Wed 03
Apr
00:00

WSW
WSW

9 / 13 mph 46 / 41°F 78% 996 mb
Low level cloud: 0%
Mid level cloud: 59%
High level cloud: 2%
Most Significant Cloud Type: medium
58%
0.03 In
06:00

WSW
WSW

15 / 32 mph 39 / 31°F 78% 994 mb
Low level cloud: 0%
Mid level cloud: 44%
High level cloud: 0%
Most Significant Cloud Type: medium
44%
0.15 In
12:00

WSW
WSW

5 / 6 mph 51 / 49°F 66% 994 mb
Low level cloud: 33%
Mid level cloud: 45%
High level cloud: 46%
Most Significant Cloud Type: low
53%
0.01 In
18:00

SW
SW

27 / 51 mph 45 / 35°F 86% 976 mb
Low level cloud: 65%
Mid level cloud: 29%
High level cloud: 0%
Most Significant Cloud Type: low
74%
0.35 In
Thu 04
Apr
00:00

NW
NW

17 / 22 mph 41 / 33°F 72% 998 mb
Low level cloud: 0%
Mid level cloud: 12%
High level cloud: 0%
Most Significant Cloud Type: medium
12%
0.05 In
06:00

SW
SW

16 / 25 mph 44 / 36°F 79% 976 mb
Low level cloud: 30%
Mid level cloud: 43%
High level cloud: 5%
Most Significant Cloud Type: low
45%
0.01 In
12:00

W
W

17 / 19 mph 48 / 41°F 54% 1007 mb
Low level cloud: 10%
Mid level cloud: 3%
High level cloud: 0%
Most Significant Cloud Type: low
10%
0.00 In
18:00

WSW
WSW

15 / 26 mph 48 / 42°F 75% 978 mb
Low level cloud: 0%
Mid level cloud: 43%
High level cloud: 50%
Most Significant Cloud Type: medium
45%
0.17 In

The day label given represents the local day relative to the local time for the location you are looking at.
(More Info)

Day

This time is corrected for local time zones and where possible for daylight saving times.
(More Info)

Local Time

The wind direction we use on this page is the direction the wind is coming from, given in a 16 point compass format.
(More Info)

Dir

This refers to the sustained average wind speed, normally averaged over a period of 10 minutes for up to 3 hrs.
(More Info)

Speed/
Gust

Temperature from our forecast perspective are fairly well defined, they are what we would expect to measure in a standard meteorological screen (in other words, shaded and well ventilated) at 2 metres above ground level.
(More Info)

Temp/
Feels Like

The relative humidity is the percent of saturation humidity, generally calculated in relation to saturated vapour density.
(More Info)

Humidity

The value given is a total predicted for the previous 3 hrs and includes the time of the forecast being looked at.
(More Info)

Precip Amount

The total amount of cloud as a percentage is derived from looking at cloud cover throughout the atmosphere and estimating how these combine when looked at from the ground.
(More Info)

Cloud Amount

Here we try to capture the feel of the weather as an image – it will never be perfect but is useful for a quick overview.
(More Info)

Weather

When we measure for forecast air pressure we are normally doing this relative to a certain height and most commonly relative to Mean Sea Level.
(More Info)

Pressure