WEATHER FOR BUSINESS

We supply weather data to businesses

Free Weather Plugin

Add this forecast to your website



Local Weather

Royston 14 Day Long Range Forecast

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

City of Glasgow, United Kingdom

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

For Royston in the coming two weeks the average daytime maximum temperature will be around 18°C, with a high for the two weeks of 21°C expected on the afternoon of Saturday 18th. The mean minimum temperature will be 8°C, dipping to its lowest on the morning of Tuesday 21st at 4°C. The fortnight ahead will have mixed weather with some days dry and some seeing a little rain. The indicators are that Wednesday 15th will have the most precipitation with an accumulation of around 4.0mm. On the whole winds are likely to be moderate.

DayLocal TimeDirSpeed/
Gust
Temp/
Feels Like
HumidityPressureCloud AmountPrecip AmountWeather
Wed 15
May
18:00

E
E

7 / 9 mph 64 / 62°F 88% 1006 mb
Low level cloud: 37%
Mid level cloud: 42%
High level cloud: 100%
Most Significant Cloud Type: low
63%
Expect 0.1 In of precipitation over the past 3 hours.
0.1 In
21:00

ENE
ENE

5 / 8 mph 55 / 54°F 97% 1008 mb
Low level cloud: 96%
Mid level cloud: 44%
High level cloud: 42%
Most Significant Cloud Type: low
100%
Expect 0.1 In of precipitation over the past 3 hours.
0.1 In
Thu 16
May
00:00

NE
NE

4 / 8 mph 52 / 51°F 98% 1008 mb
Low level cloud: 51%
Mid level cloud: 46%
High level cloud: 31%
Most Significant Cloud Type: low
71%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
03:00

ENE
ENE

4 / 7 mph 50 / 49°F 99% 1009 mb
Low level cloud: 80%
Mid level cloud: 44%
High level cloud: 12%
Most Significant Cloud Type: low
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
06:00

ENE
ENE

4 / 6 mph 53 / 52°F 97% 1009 mb
Low level cloud: 82%
Mid level cloud: 46%
High level cloud: 7%
Most Significant Cloud Type: low
99%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
09:00

NE
NE

6 / 6 mph 57 / 55°F 90% 1010 mb
Low level cloud: 92%
Mid level cloud: 20%
High level cloud: 6%
Most Significant Cloud Type: low
99%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
12:00

ENE
ENE

7 / 8 mph 62 / 62°F 77% 1010 mb
Low level cloud: 91%
Mid level cloud: 45%
High level cloud: 10%
Most Significant Cloud Type: low
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
15:00

ENE
ENE

10 / 11 mph 63 / 63°F 78% 1010 mb
Low level cloud: 80%
Mid level cloud: 31%
High level cloud: 14%
Most Significant Cloud Type: low
92%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
18:00

ENE
ENE

10 / 11 mph 62 / 61°F 81% 1010 mb
Low level cloud: 47%
Mid level cloud: 2%
High level cloud: 4%
Most Significant Cloud Type: low
48%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
21:00

ENE
ENE

8 / 13 mph 54 / 49°F 95% 1012 mb
Low level cloud: 46%
Mid level cloud: 6%
High level cloud: 0%
Most Significant Cloud Type: low
48%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
Fri 17
May
00:00

ENE
ENE

7 / 12 mph 50 / 47°F 94% 1013 mb
Low level cloud: 44%
Mid level cloud: 3%
High level cloud: 3%
Most Significant Cloud Type: low
45%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
03:00

NE
NE

6 / 11 mph 48 / 46°F 94% 1013 mb
Low level cloud: 40%
Mid level cloud: 6%
High level cloud: 16%
Most Significant Cloud Type: low
43%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
06:00

NE
NE

6 / 8 mph 53 / 50°F 90% 1013 mb
Low level cloud: 25%
Mid level cloud: 46%
High level cloud: 39%
Most Significant Cloud Type: low
45%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
09:00

NE
NE

10 / 11 mph 62 / 61°F 72% 1013 mb
Low level cloud: 29%
Mid level cloud: 18%
High level cloud: 85%
Most Significant Cloud Type: low
45%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
12:00

NE
NE

12 / 13 mph 66 / 65°F 66% 1013 mb
Low level cloud: 39%
Mid level cloud: 10%
High level cloud: 33%
Most Significant Cloud Type: low
46%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
15:00

E
E

10 / 12 mph 68 / 67°F 63% 1013 mb
Low level cloud: 14%
Mid level cloud: 12%
High level cloud: 96%
Most Significant Cloud Type: low
29%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
18:00

ENE
ENE

7 / 8 mph 66 / 64°F 74% 1014 mb
Low level cloud: 11%
Mid level cloud: 10%
High level cloud: 32%
Most Significant Cloud Type: low
18%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
21:00

ENE
ENE

4 / 6 mph 55 / 53°F 94% 1015 mb
Low level cloud: 9%
Mid level cloud: 20%
High level cloud: 22%
Most Significant Cloud Type: low
18%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
Sat 18
May
00:00

ENE
ENE

2 / 5 mph 50 / 50°F 95% 1015 mb
Low level cloud: 15%
Mid level cloud: 26%
High level cloud: 14%
Most Significant Cloud Type: low
25%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
03:00

SSE
SSE

0 / 1 mph 48 / 48°F 96% 1016 mb
Low level cloud: 23%
Mid level cloud: 18%
High level cloud: 5%
Most Significant Cloud Type: low
29%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
06:00

SW
SW

2 / 2 mph 55 / 53°F 91% 1016 mb
Low level cloud: 37%
Mid level cloud: 22%
High level cloud: 2%
Most Significant Cloud Type: low
44%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
09:00

W
W

2 / 2 mph 66 / 63°F 75% 1016 mb
Low level cloud: 53%
Mid level cloud: 19%
High level cloud: 7%
Most Significant Cloud Type: low
60%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
12:00

W
W

3 / 3 mph 70 / 67°F 67% 1016 mb
Low level cloud: 36%
Mid level cloud: 10%
High level cloud: 13%
Most Significant Cloud Type: low
41%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
15:00

SE
SE

2 / 2 mph 69 / 66°F 77% 1016 mb
Low level cloud: 30%
Mid level cloud: 25%
High level cloud: 9%
Most Significant Cloud Type: low
39%
Expect 0.1 In of precipitation over the past 3 hours.
0.1 In
18:00

E
E

3 / 4 mph 61 / 61°F 86% 1017 mb
Low level cloud: 84%
Mid level cloud: 46%
High level cloud: 33%
Most Significant Cloud Type: low
100%
Expect 0.1 In of precipitation over the past 3 hours.
0.1 In
21:00

NE
NE

3 / 4 mph 55 / 54°F 92% 1018 mb
Low level cloud: 69%
Mid level cloud: 65%
High level cloud: 10%
Most Significant Cloud Type: low
93%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
Sun 19
May
00:00

NE
NE

3 / 4 mph 53 / 53°F 90% 1019 mb
Low level cloud: 46%
Mid level cloud: 57%
High level cloud: 33%
Most Significant Cloud Type: low
70%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
03:00

NE
NE

3 / 4 mph 52 / 52°F 91% 1019 mb
Low level cloud: 67%
Mid level cloud: 61%
High level cloud: 37%
Most Significant Cloud Type: low
92%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
06:00

ENE
ENE

4 / 5 mph 52 / 51°F 87% 1020 mb
Low level cloud: 84%
Mid level cloud: 60%
High level cloud: 32%
Most Significant Cloud Type: low
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
09:00

ENE
ENE

7 / 8 mph 53 / 51°F 81% 1021 mb
Low level cloud: 92%
Mid level cloud: 79%
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

ENE
ENE

7 / 8 mph 51 / 49°F 82% 1022 mb
Low level cloud: 100%
Mid level cloud: 82%
High level cloud: 32%
Most Significant Cloud Type: low
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
15:00

ENE
ENE

7 / 8 mph 52 / 49°F 84% 1022 mb
Low level cloud: 93%
Mid level cloud: 57%
High level cloud: 22%
Most Significant Cloud Type: low
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
18:00

ENE
ENE

6 / 7 mph 52 / 50°F 86% 1022 mb
Low level cloud: 92%
Mid level cloud: 44%
High level cloud: 95%
Most Significant Cloud Type: low
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
21:00

ENE
ENE

6 / 7 mph 50 / 48°F 84% 1023 mb
Low level cloud: 90%
Mid level cloud: 45%
High level cloud: 18%
Most Significant Cloud Type: low
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
Mon 20
May
00:00

ENE
ENE

5 / 6 mph 48 / 46°F 76% 1023 mb
Low level cloud: 61%
Mid level cloud: 25%
High level cloud: 7%
Most Significant Cloud Type: low
70%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
03:00

ENE
ENE

4 / 7 mph 43 / 40°F 92% 1023 mb
Low level cloud: 10%
Mid level cloud: 17%
High level cloud: 7%
Most Significant Cloud Type: low
16%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
06:00

ENE
ENE

5 / 6 mph 46 / 43°F 84% 1023 mb
Low level cloud: 11%
Mid level cloud: 4%
High level cloud: 2%
Most Significant Cloud Type: low
12%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
09:00

ENE
ENE

8 / 9 mph 55 / 52°F 62% 1023 mb
Low level cloud: 0%
Mid level cloud: 6%
High level cloud: 0%
Most Significant Cloud Type: medium
5%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
12:00

ENE
ENE

9 / 10 mph 61 / 59°F 49% 1022 mb
Low level cloud: 0%
Mid level cloud: 6%
High level cloud: 6%
Most Significant Cloud Type: medium
6%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
15:00

ENE
ENE

9 / 10 mph 62 / 61°F 47% 1021 mb
Low level cloud: 0%
Mid level cloud: 4%
High level cloud: 2%
Most Significant Cloud Type: medium
3%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
18:00

ENE
ENE

9 / 10 mph 58 / 55°F 57% 1020 mb
Low level cloud: 0%
Mid level cloud: 5%
High level cloud: 0%
Most Significant Cloud Type: medium
4%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
21:00

ENE
ENE

7 / 8 mph 50 / 47°F 85% 1021 mb
Low level cloud: 0%
Mid level cloud: 1%
High level cloud: 0%
Most Significant Cloud Type: high
0%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
Tue 21
May
00:00

ENE
ENE

6 / 11 mph 41 / 37°F 93% 1021 mb
Low level cloud: 10%
Mid level cloud: 0%
High level cloud: 0%
Most Significant Cloud Type: low
10%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
03:00

ENE
ENE

6 / 10 mph 39 / 35°F 94% 1020 mb
Low level cloud: 13%
Mid level cloud: 3%
High level cloud: 0%
Most Significant Cloud Type: low
14%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
06:00

NE
NE

5 / 6 mph 46 / 42°F 82% 1018 mb
Low level cloud: 81%
Mid level cloud: 5%
High level cloud: 0%
Most Significant Cloud Type: low
83%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
09:00

ENE
ENE

7 / 8 mph 49 / 46°F 83% 1018 mb
Low level cloud: 80%
Mid level cloud: 0%
High level cloud: 7%
Most Significant Cloud Type: low
80%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
12:00

ENE
ENE

7 / 9 mph 54 / 52°F 75% 1017 mb
Low level cloud: 84%
Mid level cloud: 7%
High level cloud: 92%
Most Significant Cloud Type: low
97%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
15:00

ENE
ENE

7 / 8 mph 64 / 61°F 63% 1016 mb
Low level cloud: 51%
Mid level cloud: 12%
High level cloud: 17%
Most Significant Cloud Type: low
57%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
18:00

ENE
ENE

4 / 6 mph 60 / 59°F 76% 1016 mb
Low level cloud: 75%
Mid level cloud: 58%
High level cloud: 19%
Most Significant Cloud Type: low
97%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
21:00

ENE
ENE

6 / 10 mph 53 / 51°F 94% 1018 mb
Low level cloud: 81%
Mid level cloud: 75%
High level cloud: 1%
Most Significant Cloud Type: low
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
DayLocal TimeDirSpeed/
Gust
Temp/
Feels Like
HumidityPressureCloud AmountPrecip AmountWeather
Wed 22
May
00:00

NNE
NNE

2 / 4 mph 54 / 55°F 98% 1008 mb
Low level cloud: 67%
Mid level cloud: 97%
High level cloud: 100%
Most Significant Cloud Type: low
100%
0.0 In
06:00

ENE
ENE

6 / 9 mph 47 / 44°F 81% 1016 mb
Low level cloud: 4%
Mid level cloud: 5%
High level cloud: 32%
Most Significant Cloud Type: medium
17%
0.0 In
12:00

NE
NE

9 / 15 mph 57 / 55°F 87% 1019 mb
Low level cloud: 20%
Mid level cloud: 79%
High level cloud: 99%
Most Significant Cloud Type: medium
100%
0.0 In
18:00

ENE
ENE

13 / 22 mph 54 / 50°F 61% 1019 mb
Low level cloud: 0%
Mid level cloud: 49%
High level cloud: 0%
Most Significant Cloud Type: medium
48%
0.0 In
Thu 23
May
00:00

ENE
ENE

7 / 13 mph 53 / 51°F 92% 1018 mb
Low level cloud: 4%
Mid level cloud: 13%
High level cloud: 37%
Most Significant Cloud Type: medium
24%
0.0 In
06:00

S
S

11 / 21 mph 55 / 52°F 84% 1012 mb
Low level cloud: 100%
Mid level cloud: 52%
High level cloud: 57%
Most Significant Cloud Type: low
100%
0.0 In
12:00

ENE
ENE

6 / 14 mph 63 / 63°F 55% 1027 mb
Low level cloud: 25%
Mid level cloud: 5%
High level cloud: 0%
Most Significant Cloud Type: low
26%
0.0 In
18:00

E
E

11 / 22 mph 63 / 63°F 71% 1024 mb
Low level cloud: 11%
Mid level cloud: 0%
High level cloud: 5%
Most Significant Cloud Type: low
12%
0.0 In
Fri 24
May
00:00

NE
NE

5 / 11 mph 48 / 46°F 94% 1029 mb
Low level cloud: 17%
Mid level cloud: 2%
High level cloud: 0%
Most Significant Cloud Type: low
17%
0.0 In
06:00

ENE
ENE

7 / 15 mph 50 / 47°F 86% 1024 mb
Low level cloud: 75%
Mid level cloud: 2%
High level cloud: 2%
Most Significant Cloud Type: low
76%
0.0 In
12:00

ENE
ENE

8 / 17 mph 66 / 66°F 60% 1025 mb
Low level cloud: 27%
Mid level cloud: 5%
High level cloud: 0%
Most Significant Cloud Type: low
29%
0.0 In
18:00

NE
NE

4 / 9 mph 67 / 67°F 67% 1020 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 35%
Most Significant Cloud Type: high
35%
0.0 In
Sat 25
May
00:00

NE
NE

7 / 14 mph 51 / 48°F 91% 1023 mb
Low level cloud: 0%
Mid level cloud: 9%
High level cloud: 0%
Most Significant Cloud Type: medium
9%
0.0 In
06:00

W
W

0 / 0 mph 58 / 58°F 88% 1020 mb
Low level cloud: 18%
Mid level cloud: 3%
High level cloud: 12%
Most Significant Cloud Type: low
20%
0.0 In
12:00

ENE
ENE

10 / 21 mph 60 / 60°F 67% 1020 mb
Low level cloud: 42%
Mid level cloud: 46%
High level cloud: 0%
Most Significant Cloud Type: low
57%
0.0 In
18:00

WSW
WSW

7 / 14 mph 68 / 68°F 63% 1016 mb
Low level cloud: 0%
Mid level cloud: 3%
High level cloud: 0%
Most Significant Cloud Type: medium
2%
0.0 In
Sun 26
May
00:00

NE
NE

4 / 9 mph 53 / 51°F 93% 1021 mb
Low level cloud: 64%
Mid level cloud: 74%
High level cloud: 32%
Most Significant Cloud Type: low
94%
0.1 In
06:00

WSW
WSW

7 / 14 mph 55 / 53°F 82% 1017 mb
Low level cloud: 7%
Mid level cloud: 28%
High level cloud: 0%
Most Significant Cloud Type: medium
46%
0.0 In
12:00

ENE
ENE

8 / 17 mph 69 / 69°F 68% 1022 mb
Low level cloud: 58%
Mid level cloud: 19%
High level cloud: 0%
Most Significant Cloud Type: low
65%
0.0 In
18:00

W
W

9 / 19 mph 58 / 57°F 63% 1017 mb
Low level cloud: 40%
Mid level cloud: 13%
High level cloud: 0%
Most Significant Cloud Type: low
44%
0.0 In
Mon 27
May
00:00

ENE
ENE

5 / 11 mph 56 / 55°F 95% 1025 mb
Low level cloud: 14%
Mid level cloud: 0%
High level cloud: 4%
Most Significant Cloud Type: low
14%
0.0 In
06:00

W
W

5 / 11 mph 54 / 53°F 82% 1018 mb
Low level cloud: 5%
Mid level cloud: 5%
High level cloud: 70%
Most Significant Cloud Type: medium
23%
0.0 In
12:00

ENE
ENE

3 / 7 mph 75 / 77°F 54% 1023 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 0%
Most Significant Cloud Type: high
0%
0.0 In
18:00

WNW
WNW

9 / 19 mph 57 / 55°F 72% 1018 mb
Low level cloud: 77%
Mid level cloud: 1%
High level cloud: 32%
Most Significant Cloud Type: low
81%
0.0 In
Tue 28
May
00:00

ENE
ENE

4 / 9 mph 65 / 65°F 79% 1019 mb
Low level cloud: 0%
Mid level cloud: 18%
High level cloud: 0%
Most Significant Cloud Type: medium
18%
0.0 In
06:00

W
W

7 / 15 mph 51 / 48°F 77% 1020 mb
Low level cloud: 16%
Mid level cloud: 0%
High level cloud: 10%
Most Significant Cloud Type: low
16%
0.0 In
12:00

ENE
ENE

13 / 26 mph 67 / 67°F 50% 1015 mb
Low level cloud: 0%
Mid level cloud: 6%
High level cloud: 5%
Most Significant Cloud Type: medium
6%
0.0 In
18:00

W
W

13 / 28 mph 53 / 48°F 82% 1017 mb
Low level cloud: 87%
Mid level cloud: 44%
High level cloud: 3%
Most Significant Cloud Type: low
100%
0.0 In
Wed 29
May
00:00

NE
NE

6 / 14 mph 55 / 53°F 78% 1014 mb
Low level cloud: 0%
Mid level cloud: 13%
High level cloud: 8%
Most Significant Cloud Type: medium
13%
0.0 In
06:00

WSW
WSW

15 / 32 mph 48 / 42°F 90% 1010 mb
Low level cloud: 94%
Mid level cloud: 66%
High level cloud: 32%
Most Significant Cloud Type: low
100%
0.0 In
12:00

ENE
ENE

11 / 22 mph 71 / 71°F 56% 1012 mb
Low level cloud: 0%
Mid level cloud: 6%
High level cloud: 0%
Most Significant Cloud Type: medium
6%
0.0 In
18:00

W
W

16 / 33 mph 53 / 49°F 73% 1009 mb
Low level cloud: 35%
Mid level cloud: 18%
High level cloud: 9%
Most Significant Cloud Type: low
42%
0.1 In
Thu 30
May
00:00

ENE
ENE

5 / 10 mph 58 / 58°F 90% 1010 mb
Low level cloud: 0%
Mid level cloud: 10%
High level cloud: 0%
Most Significant Cloud Type: medium
10%
0.0 In
06:00

W
W

9 / 18 mph 51 / 47°F 77% 1010 mb
Low level cloud: 23%
Mid level cloud: 28%
High level cloud: 72%
Most Significant Cloud Type: low
41%
0.0 In
12:00

E
E

3 / 6 mph 76 / 78°F 58% 1005 mb
Low level cloud: 20%
Mid level cloud: 14%
High level cloud: 100%
Most Significant Cloud Type: low
37%
0.0 In
18:00

WSW
WSW

9 / 19 mph 57 / 55°F 63% 1011 mb
Low level cloud: 0%
Mid level cloud: 100%
High level cloud: 98%
Most Significant Cloud Type: medium
100%
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