Fast Forecast

WEATHER FOR BUSINESS

We supply weather data to businesses

Free Weather Plugin

Add this forecast to your website



Local Weather

Dam Side 14 Day Long Range Forecast

14 Day weather providing an extended long range forecast outlook for Dam Side

Lancashire, United Kingdom

Long range weather outlook for Dam Side includes 14 day forecast summary:

For Dam Side in the coming two weeks the average daytime maximum temperature will be around 13°C, with a high for the two weeks of 15°C expected on the afternoon of Thursday 6th. The mean minimum temperature will be 9°C, dipping to its lowest on the morning of Thursday 13th at 5°C. The next 14 days will have some days seeing a little precipitation and some days with rain. The indicators are that Monday 3rd will have the most precipitation with an accumulation of around 24.0mm. On the whole winds are likely to be moderate. The strongest wind will be felt on the morning of Monday 3rd, coming from a south westerly direction, and reaching around 26mph.

DayLocal TimeDirSpeed/
Gust		Temp/
Feels Like		HumidityPressureCloud AmountPrecip AmountWeather
Mon 03
Nov		21:00

SSW
SSW

 27 / 42 mph 56 / 51°F 89% 1002 mb
Low level cloud: 100%
Mid level cloud: 79%
High level cloud: 0%
Most Significant Cloud Type: low
100%
Expect 0.1 In of precipitation over the past 3 hours.
0.1 In
Tue 04
Nov		00:00

SSW
SSW

 24 / 41 mph 55 / 50°F 92% 1003 mb
Low level cloud: 100%
Mid level cloud: 95%
High level cloud: 17%
Most Significant Cloud Type: low
100%
Expect 0.1 In of precipitation over the past 3 hours.
0.1 In
03:00

SW
SW

 19 / 35 mph 55 / 50°F 94% 1004 mb
Low level cloud: 99%
Mid level cloud: 64%
High level cloud: 32%
Most Significant Cloud Type: low
100%
Expect 0.1 In of precipitation over the past 3 hours.
0.1 In
06:00

SSW
SSW

 13 / 24 mph 54 / 50°F 96% 1004 mb
Low level cloud: 95%
Mid level cloud: 84%
High level cloud: 69%
Most Significant Cloud Type: low
100%
Expect 0.2 In of precipitation over the past 3 hours.
0.2 In
09:00

S
S

 20 / 34 mph 55 / 51°F 89% 1004 mb
Low level cloud: 89%
Mid level cloud: 59%
High level cloud: 32%
Most Significant Cloud Type: low
100%
Expect 0.2 In of precipitation over the past 3 hours.
0.2 In
12:00

S
S

 19 / 27 mph 57 / 53°F 90% 1004 mb
Low level cloud: 89%
Mid level cloud: 46%
High level cloud: 37%
Most Significant Cloud Type: low
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
15:00

S
S

 18 / 23 mph 58 / 54°F 90% 1004 mb
Low level cloud: 87%
Mid level cloud: 28%
High level cloud: 81%
Most Significant Cloud Type: low
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
18:00

SSE
SSE

 13 / 18 mph 57 / 54°F 93% 1004 mb
Low level cloud: 77%
Mid level cloud: 46%
High level cloud: 20%
Most Significant Cloud Type: low
95%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
21:00

SSE
SSE

 11 / 17 mph 56 / 53°F 94% 1004 mb
Low level cloud: 91%
Mid level cloud: 27%
High level cloud: 33%
Most Significant Cloud Type: low
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
Wed 05
Nov		00:00

SE
SE

 7 / 10 mph 55 / 54°F 95% 1005 mb
Low level cloud: 76%
Mid level cloud: 5%
High level cloud: 100%
Most Significant Cloud Type: low
90%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
03:00

ESE
ESE

 6 / 10 mph 55 / 53°F 94% 1004 mb
Low level cloud: 95%
Mid level cloud: 47%
High level cloud: 100%
Most Significant Cloud Type: low
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
06:00

SE
SE

 9 / 16 mph 54 / 52°F 94% 1003 mb
Low level cloud: 97%
Mid level cloud: 93%
High level cloud: 100%
Most Significant Cloud Type: low
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
09:00

SSE
SSE

 13 / 22 mph 55 / 52°F 96% 1003 mb
Low level cloud: 100%
Mid level cloud: 100%
High level cloud: 100%
Most Significant Cloud Type: low
100%
Expect 0.1 In of precipitation over the past 3 hours.
0.1 In
12:00

SSE
SSE

 14 / 22 mph 57 / 54°F 93% 1003 mb
Low level cloud: 44%
Mid level cloud: 84%
High level cloud: 98%
Most Significant Cloud Type: low
85%
Expect 0.2 In of precipitation over the past 3 hours.
0.2 In
15:00

SSE
SSE

 18 / 29 mph 58 / 54°F 83% 1002 mb
Low level cloud: 31%
Mid level cloud: 100%
High level cloud: 99%
Most Significant Cloud Type: medium
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
18:00

SSE
SSE

 19 / 31 mph 57 / 53°F 87% 1003 mb
Low level cloud: 44%
Mid level cloud: 19%
High level cloud: 19%
Most Significant Cloud Type: low
52%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
21:00

SE
SE

 11 / 17 mph 56 / 53°F 89% 1004 mb
Low level cloud: 18%
Mid level cloud: 96%
High level cloud: 13%
Most Significant Cloud Type: medium
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
Thu 06
Nov		00:00

ESE
ESE

 7 / 13 mph 55 / 53°F 88% 1003 mb
Low level cloud: 24%
Mid level cloud: 76%
High level cloud: 33%
Most Significant Cloud Type: medium
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
03:00

ESE
ESE

 7 / 15 mph 54 / 51°F 87% 1003 mb
Low level cloud: 1%
Mid level cloud: 47%
High level cloud: 14%
Most Significant Cloud Type: medium
49%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
06:00

ESE
ESE

 7 / 14 mph 53 / 51°F 86% 1003 mb
Low level cloud: 0%
Mid level cloud: 44%
High level cloud: 100%
Most Significant Cloud Type: medium
48%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
09:00

ESE
ESE

 8 / 15 mph 55 / 53°F 86% 1003 mb
Low level cloud: 85%
Mid level cloud: 44%
High level cloud: 100%
Most Significant Cloud Type: low
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
12:00

SSE
SSE

 11 / 17 mph 57 / 55°F 86% 1004 mb
Low level cloud: 72%
Mid level cloud: 14%
High level cloud: 22%
Most Significant Cloud Type: low
80%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
15:00

S
S

 5 / 7 mph 59 / 58°F 89% 1004 mb
Low level cloud: 80%
Mid level cloud: 20%
High level cloud: 15%
Most Significant Cloud Type: low
88%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
18:00

SE
SE

 3 / 5 mph 58 / 58°F 92% 1005 mb
Low level cloud: 64%
Mid level cloud: 9%
High level cloud: 68%
Most Significant Cloud Type: low
75%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
21:00

ESE
ESE

 4 / 6 mph 56 / 56°F 93% 1005 mb
Low level cloud: 61%
Mid level cloud: 45%
High level cloud: 11%
Most Significant Cloud Type: low
77%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
Fri 07
Nov		00:00

ESE
ESE

 3 / 6 mph 54 / 54°F 92% 1005 mb
Low level cloud: 40%
Mid level cloud: 41%
High level cloud: 16%
Most Significant Cloud Type: low
56%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
03:00

E
E

 5 / 9 mph 53 / 51°F 92% 1005 mb
Low level cloud: 57%
Mid level cloud: 27%
High level cloud: 33%
Most Significant Cloud Type: low
70%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
06:00

E
E

 5 / 10 mph 52 / 50°F 90% 1005 mb
Low level cloud: 93%
Mid level cloud: 27%
High level cloud: 4%
Most Significant Cloud Type: low
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
09:00

E
E

 4 / 8 mph 54 / 53°F 89% 1005 mb
Low level cloud: 42%
Mid level cloud: 44%
High level cloud: 4%
Most Significant Cloud Type: low
57%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
12:00

ESE
ESE

 3 / 5 mph 57 / 57°F 86% 1005 mb
Low level cloud: 30%
Mid level cloud: 45%
High level cloud: 26%
Most Significant Cloud Type: low
49%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
15:00

ESE
ESE

 1 / 1 mph 58 / 58°F 87% 1005 mb
Low level cloud: 72%
Mid level cloud: 45%
High level cloud: 18%
Most Significant Cloud Type: low
89%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
18:00

ESE
ESE

 3 / 4 mph 57 / 58°F 91% 1006 mb
Low level cloud: 79%
Mid level cloud: 98%
High level cloud: 100%
Most Significant Cloud Type: low
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
21:00

ENE
ENE

 4 / 6 mph 55 / 55°F 91% 1007 mb
Low level cloud: 37%
Mid level cloud: 21%
High level cloud: 4%
Most Significant Cloud Type: low
44%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
Sat 08
Nov		00:00

ENE
ENE

 3 / 5 mph 53 / 53°F 92% 1007 mb
Low level cloud: 84%
Mid level cloud: 61%
High level cloud: 7%
Most Significant Cloud Type: low
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
03:00

NE
NE

 4 / 7 mph 52 / 51°F 95% 1007 mb
Low level cloud: 98%
Mid level cloud: 64%
High level cloud: 100%
Most Significant Cloud Type: low
100%
Expect 0.1 In of precipitation over the past 3 hours.
0.1 In
06:00

NE
NE

 4 / 9 mph 51 / 50°F 94% 1008 mb
Low level cloud: 91%
Mid level cloud: 71%
High level cloud: 33%
Most Significant Cloud Type: low
100%
Expect 0.1 In of precipitation over the past 3 hours.
0.1 In
09:00

NE
NE

 6 / 12 mph 53 / 51°F 91% 1009 mb
Low level cloud: 69%
Mid level cloud: 46%
High level cloud: 100%
Most Significant Cloud Type: low
97%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
12:00

ENE
ENE

 5 / 8 mph 55 / 54°F 86% 1009 mb
Low level cloud: 83%
Mid level cloud: 44%
High level cloud: 30%
Most Significant Cloud Type: low
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
15:00

E
E

 4 / 6 mph 56 / 56°F 88% 1010 mb
Low level cloud: 85%
Mid level cloud: 43%
High level cloud: 6%
Most Significant Cloud Type: low
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
18:00

E
E

 5 / 7 mph 55 / 54°F 87% 1011 mb
Low level cloud: 53%
Mid level cloud: 38%
High level cloud: 2%
Most Significant Cloud Type: low
66%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
21:00

E
E

 5 / 6 mph 54 / 53°F 86% 1012 mb
Low level cloud: 36%
Mid level cloud: 46%
High level cloud: 32%
Most Significant Cloud Type: low
56%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
Sun 09
Nov		00:00

SE
SE

 4 / 7 mph 50 / 49°F 89% 1012 mb
Low level cloud: 63%
Mid level cloud: 42%
High level cloud: 7%
Most Significant Cloud Type: low
78%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
03:00

S
S

 6 / 13 mph 48 / 45°F 94% 1013 mb
Low level cloud: 96%
Mid level cloud: 26%
High level cloud: 7%
Most Significant Cloud Type: low
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
06:00

S
S

 7 / 14 mph 47 / 44°F 95% 1013 mb
Low level cloud: 97%
Mid level cloud: 46%
High level cloud: 55%
Most Significant Cloud Type: low
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
09:00

S
S

 5 / 9 mph 50 / 48°F 94% 1014 mb
Low level cloud: 60%
Mid level cloud: 61%
High level cloud: 34%
Most Significant Cloud Type: low
85%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
12:00

SSE
SSE

 5 / 7 mph 53 / 51°F 88% 1015 mb
Low level cloud: 75%
Mid level cloud: 32%
High level cloud: 20%
Most Significant Cloud Type: low
88%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
15:00

S
S

 5 / 7 mph 54 / 53°F 88% 1015 mb
Low level cloud: 30%
Mid level cloud: 27%
High level cloud: 65%
Most Significant Cloud Type: low
46%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
18:00

SE
SE

 5 / 6 mph 53 / 52°F 90% 1016 mb
Low level cloud: 62%
Mid level cloud: 28%
High level cloud: 21%
Most Significant Cloud Type: low
74%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
21:00

ESE
ESE

 5 / 8 mph 51 / 49°F 90% 1016 mb
Low level cloud: 11%
Mid level cloud: 2%
High level cloud: 50%
Most Significant Cloud Type: low
17%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
DayLocal TimeDirSpeed/
Gust		Temp/
Feels Like		HumidityPressureCloud AmountPrecip AmountWeather
Mon 10
Nov		00:00

ESE
ESE

 5 / 11 mph 46 / 43°F 79% 1025 mb
Low level cloud: 0%
Mid level cloud: 2%
High level cloud: 3%
Most Significant Cloud Type: medium
2%
0.0 In
06:00

WSW
WSW

 2 / 5 mph 50 / 50°F 91% 1023 mb
Low level cloud: 24%
Mid level cloud: 100%
High level cloud: 97%
Most Significant Cloud Type: medium
100%
0.0 In
12:00

ESE
ESE

 12 / 25 mph 49 / 44°F 75% 1003 mb
Low level cloud: 13%
Mid level cloud: 44%
High level cloud: 65%
Most Significant Cloud Type: medium
81%
0.0 In
18:00

WSW
WSW

 13 / 27 mph 51 / 46°F 88% 1014 mb
Low level cloud: 40%
Mid level cloud: 4%
High level cloud: 0%
Most Significant Cloud Type: low
41%
0.0 In
Tue 11
Nov		00:00

SE
SE

 4 / 9 mph 47 / 45°F 91% 1006 mb
Low level cloud: 39%
Mid level cloud: 1%
High level cloud: 0%
Most Significant Cloud Type: low
39%
0.0 In
06:00

SE
SE

 11 / 20 mph 45 / 40°F 89% 1006 mb
Low level cloud: 3%
Mid level cloud: 18%
High level cloud: 9%
Most Significant Cloud Type: medium
27%
0.0 In
12:00

SSE
SSE

 6 / 12 mph 51 / 49°F 82% 1014 mb
Low level cloud: 84%
Mid level cloud: 40%
High level cloud: 29%
Most Significant Cloud Type: low
100%
0.0 In
18:00

SE
SE

 2 / 4 mph 52 / 53°F 86% 1007 mb
Low level cloud: 55%
Mid level cloud: 43%
High level cloud: 0%
Most Significant Cloud Type: low
70%
0.0 In
Wed 12
Nov		00:00

E
E

 6 / 12 mph 49 / 46°F 85% 1021 mb
Low level cloud: 0%
Mid level cloud: 3%
High level cloud: 12%
Most Significant Cloud Type: medium
3%
0.0 In
06:00

ENE
ENE

 9 / 17 mph 44 / 40°F 88% 1011 mb
Low level cloud: 0%
Mid level cloud: 44%
High level cloud: 32%
Most Significant Cloud Type: medium
46%
0.0 In
12:00

E
E

 6 / 11 mph 52 / 50°F 78% 1024 mb
Low level cloud: 0%
Mid level cloud: 2%
High level cloud: 2%
Most Significant Cloud Type: medium
2%
0.0 In
18:00

E
E

 15 / 28 mph 50 / 44°F 86% 1018 mb
Low level cloud: 38%
Mid level cloud: 51%
High level cloud: 100%
Most Significant Cloud Type: low
68%
0.0 In
Thu 13
Nov		00:00

E
E

 7 / 13 mph 46 / 42°F 88% 1025 mb
Low level cloud: 3%
Mid level cloud: 4%
High level cloud: 21%
Most Significant Cloud Type: low
7%
0.0 In
06:00

E
E

 19 / 36 mph 49 / 43°F 83% 1023 mb
Low level cloud: 81%
Mid level cloud: 89%
High level cloud: 18%
Most Significant Cloud Type: low
100%
0.0 In
12:00

E
E

 10 / 19 mph 50 / 47°F 76% 1024 mb
Low level cloud: 52%
Mid level cloud: 0%
High level cloud: 0%
Most Significant Cloud Type: low
52%
0.0 In
18:00

E
E

 23 / 44 mph 52 / 46°F 80% 1023 mb
Low level cloud: 67%
Mid level cloud: 48%
High level cloud: 18%
Most Significant Cloud Type: low
86%
0.0 In
Fri 14
Nov		00:00

ENE
ENE

 8 / 15 mph 41 / 37°F 89% 1022 mb
Low level cloud: 7%
Mid level cloud: 2%
High level cloud: 0%
Most Significant Cloud Type: low
7%
0.0 In
06:00

E
E

 24 / 47 mph 47 / 39°F 77% 1018 mb
Low level cloud: 88%
Mid level cloud: 7%
High level cloud: 2%
Most Significant Cloud Type: low
90%
0.0 In
12:00

E
E

 10 / 20 mph 50 / 45°F 77% 1022 mb
Low level cloud: 46%
Mid level cloud: 0%
High level cloud: 18%
Most Significant Cloud Type: low
48%
0.0 In
18:00

E
E

 20 / 39 mph 51 / 45°F 79% 1015 mb
Low level cloud: 98%
Mid level cloud: 26%
High level cloud: 0%
Most Significant Cloud Type: low
100%
0.0 In
Sat 15
Nov		00:00

NE
NE

 10 / 19 mph 42 / 36°F 85% 1023 mb
Low level cloud: 2%
Mid level cloud: 0%
High level cloud: 100%
Most Significant Cloud Type: medium
8%
0.0 In
06:00

ENE
ENE

 17 / 33 mph 45 / 38°F 87% 1014 mb
Low level cloud: 46%
Mid level cloud: 91%
High level cloud: 31%
Most Significant Cloud Type: low
81%
0.1 In
12:00

ENE
ENE

 15 / 30 mph 48 / 42°F 76% 1025 mb
Low level cloud: 27%
Mid level cloud: 4%
High level cloud: 20%
Most Significant Cloud Type: low
30%
0.0 In
18:00

ENE
ENE

 17 / 34 mph 48 / 42°F 79% 1018 mb
Low level cloud: 19%
Mid level cloud: 29%
High level cloud: 33%
Most Significant Cloud Type: low
32%
0.1 In
Sun 16
Nov		00:00

NE
NE

 13 / 26 mph 43 / 36°F 80% 1027 mb
Low level cloud: 11%
Mid level cloud: 6%
High level cloud: 0%
Most Significant Cloud Type: low
12%
0.0 In
06:00

ENE
ENE

 17 / 32 mph 43 / 35°F 74% 1023 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 19%
Most Significant Cloud Type: high
19%
0.0 In
12:00

NE
NE

 11 / 22 mph 49 / 45°F 74% 1029 mb
Low level cloud: 4%
Mid level cloud: 0%
High level cloud: 33%
Most Significant Cloud Type: low
7%
0.0 In
18:00

ENE
ENE

 14 / 27 mph 46 / 40°F 71% 1028 mb
Low level cloud: 27%
Mid level cloud: 0%
High level cloud: 0%
Most Significant Cloud Type: low
26%
0.0 In
Mon 17
Nov		00:00

NE
NE

 1 / 3 mph 40 / 40°F 83% 1029 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 0%
Most Significant Cloud Type: high
0%
0.0 In
06:00

ENE
ENE

 10 / 20 mph 44 / 39°F 67% 1031 mb
Low level cloud: 71%
Mid level cloud: 0%
High level cloud: 0%
Most Significant Cloud Type: low
71%
0.0 In
12:00

W
W

 14 / 28 mph 54 / 50°F 82% 1019 mb
Low level cloud: 74%
Mid level cloud: 69%
High level cloud: 100%
Most Significant Cloud Type: low
100%
0.0 In
18:00

ENE
ENE

 15 / 29 mph 47 / 41°F 63% 1034 mb
Low level cloud: 89%
Mid level cloud: 0%
High level cloud: 0%
Most Significant Cloud Type: low
89%
0.0 In
Tue 18
Nov		00:00

NW
NW

 15 / 31 mph 47 / 41°F 86% 999 mb
Low level cloud: 95%
Mid level cloud: 85%
High level cloud: 0%
Most Significant Cloud Type: low
100%
0.4 In
06:00

NNE
NNE

 7 / 15 mph 42 / 37°F 76% 1036 mb
Low level cloud: 88%
Mid level cloud: 0%
High level cloud: 0%
Most Significant Cloud Type: low
87%
0.0 In
12:00

N
N

 17 / 35 mph 43 / 35°F 85% 1004 mb
Low level cloud: 87%
Mid level cloud: 30%
High level cloud: 0%
Most Significant Cloud Type: low
97%
0.0 In
18:00

ENE
ENE

 8 / 15 mph 47 / 43°F 76% 1039 mb
Low level cloud: 4%
Mid level cloud: 0%
High level cloud: 0%
Most Significant Cloud Type: low
3%
0.0 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