WEATHER FOR BUSINESS

We supply weather data to businesses

Free Weather Plugin

Add this forecast to your website



Local Weather

East Wittering 14 Day Long Range Forecast

14 Day weather providing an extended long range forecast outlook for East Wittering

West Sussex, United Kingdom

Long range weather outlook for East Wittering includes 14 day forecast summary:

The next 14 day outlook for East Wittering shows the average daytime maximum temperature will be around 18°C, with a high for the two weeks of 22°C expected on the afternoon of Monday 20th. The mean minimum temperature will be 13°C, dipping to its lowest on the morning of Monday 20th at 9°C. The coming 14 days will have most days seeing a little rain. Current predictions suggest Wednesday 22nd will have the most precipitation with an accumulation of around 7.0mm. On the whole winds are likely to be moderate.

DayLocal TimeDirSpeed/
Gust
Temp/
Feels Like
HumidityPressureCloud AmountPrecip AmountWeather
Fri 17
May
18:00

SW
SW

3 / 4 mph 62 / 60°F 80% 1011 mb
Low level cloud: 0%
Mid level cloud: 79%
High level cloud: 100%
Most Significant Cloud Type: medium
83%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
21:00

WNW
WNW

5 / 8 mph 58 / 58°F 82% 1012 mb
Low level cloud: 0%
Mid level cloud: 95%
High level cloud: 100%
Most Significant Cloud Type: medium
98%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
Sat 18
May
00:00

WNW
WNW

7 / 11 mph 58 / 56°F 84% 1012 mb
Low level cloud: 0%
Mid level cloud: 48%
High level cloud: 50%
Most Significant Cloud Type: medium
50%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
03:00

WNW
WNW

5 / 9 mph 57 / 56°F 88% 1012 mb
Low level cloud: 38%
Mid level cloud: 76%
High level cloud: 46%
Most Significant Cloud Type: low
69%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
06:00

NNW
NNW

5 / 7 mph 56 / 55°F 93% 1013 mb
Low level cloud: 64%
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
09:00

NNE
NNE

4 / 5 mph 59 / 57°F 91% 1013 mb
Low level cloud: 36%
Mid level cloud: 71%
High level cloud: 100%
Most Significant Cloud Type: low
72%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
12:00

NNW
NNW

3 / 4 mph 61 / 60°F 88% 1013 mb
Low level cloud: 86%
Mid level cloud: 93%
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

WSW
WSW

2 / 3 mph 63 / 62°F 85% 1013 mb
Low level cloud: 78%
Mid level cloud: 15%
High level cloud: 33%
Most Significant Cloud Type: low
86%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
18:00

W
W

7 / 9 mph 63 / 61°F 89% 1013 mb
Low level cloud: 51%
Mid level cloud: 7%
High level cloud: 32%
Most Significant Cloud Type: low
57%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
21:00

W
W

7 / 10 mph 59 / 59°F 91% 1014 mb
Low level cloud: 11%
Mid level cloud: 16%
High level cloud: 98%
Most Significant Cloud Type: medium
48%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
Sun 19
May
00:00

NNW
NNW

6 / 9 mph 58 / 58°F 91% 1014 mb
Low level cloud: 9%
Mid level cloud: 22%
High level cloud: 27%
Most Significant Cloud Type: low
20%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
03:00

NNE
NNE

9 / 15 mph 56 / 54°F 94% 1014 mb
Low level cloud: 31%
Mid level cloud: 13%
High level cloud: 33%
Most Significant Cloud Type: low
39%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
06:00

NE
NE

10 / 15 mph 56 / 52°F 91% 1015 mb
Low level cloud: 30%
Mid level cloud: 18%
High level cloud: 1%
Most Significant Cloud Type: low
36%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
09:00

ENE
ENE

10 / 13 mph 59 / 56°F 88% 1016 mb
Low level cloud: 33%
Mid level cloud: 17%
High level cloud: 0%
Most Significant Cloud Type: low
39%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
12:00

E
E

7 / 9 mph 63 / 62°F 81% 1015 mb
Low level cloud: 2%
Mid level cloud: 7%
High level cloud: 0%
Most Significant Cloud Type: medium
12%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
15:00

SSE
SSE

5 / 7 mph 66 / 64°F 76% 1014 mb
Low level cloud: 2%
Mid level cloud: 13%
High level cloud: 2%
Most Significant Cloud Type: medium
20%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
18:00

ESE
ESE

3 / 4 mph 63 / 62°F 81% 1015 mb
Low level cloud: 80%
Mid level cloud: 53%
High level cloud: 0%
Most Significant Cloud Type: low
98%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
21:00

NE
NE

8 / 14 mph 59 / 59°F 83% 1015 mb
Low level cloud: 55%
Mid level cloud: 28%
High level cloud: 0%
Most Significant Cloud Type: low
64%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
Mon 20
May
00:00

NE
NE

11 / 17 mph 56 / 53°F 90% 1015 mb
Low level cloud: 2%
Mid level cloud: 1%
High level cloud: 0%
Most Significant Cloud Type: low
2%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
03:00

NE
NE

13 / 24 mph 51 / 47°F 85% 1014 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 0%
Most Significant Cloud Type: high
0%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
06:00

NE
NE

15 / 28 mph 50 / 44°F 81% 1014 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 0%
Most Significant Cloud Type: high
0%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
09:00

NE
NE

14 / 16 mph 63 / 62°F 76% 1014 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 0%
Most Significant Cloud Type: high
0%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
12:00

ENE
ENE

10 / 12 mph 70 / 68°F 74% 1013 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
15:00

ESE
ESE

10 / 11 mph 71 / 70°F 77% 1011 mb
Low level cloud: 1%
Mid level cloud: 16%
High level cloud: 0%
Most Significant Cloud Type: medium
17%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
18:00

ESE
ESE

9 / 11 mph 68 / 66°F 86% 1011 mb
Low level cloud: 1%
Mid level cloud: 12%
High level cloud: 0%
Most Significant Cloud Type: medium
15%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
21:00

ENE
ENE

10 / 12 mph 63 / 63°F 88% 1011 mb
Low level cloud: 2%
Mid level cloud: 9%
High level cloud: 0%
Most Significant Cloud Type: medium
14%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
Tue 21
May
00:00

ENE
ENE

11 / 15 mph 55 / 52°F 88% 1010 mb
Low level cloud: 11%
Mid level cloud: 5%
High level cloud: 0%
Most Significant Cloud Type: low
13%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
03:00

NE
NE

10 / 14 mph 53 / 50°F 87% 1009 mb
Low level cloud: 5%
Mid level cloud: 3%
High level cloud: 7%
Most Significant Cloud Type: low
6%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
06:00

NE
NE

11 / 15 mph 52 / 47°F 81% 1009 mb
Low level cloud: 0%
Mid level cloud: 3%
High level cloud: 32%
Most Significant Cloud Type: medium
4%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
09:00

NE
NE

8 / 11 mph 57 / 53°F 72% 1010 mb
Low level cloud: 0%
Mid level cloud: 21%
High level cloud: 34%
Most Significant Cloud Type: medium
22%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
12:00

SE
SE

5 / 5 mph 63 / 61°F 77% 1010 mb
Low level cloud: 0%
Mid level cloud: 17%
High level cloud: 100%
Most Significant Cloud Type: medium
21%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
15:00

SSW
SSW

4 / 4 mph 67 / 64°F 81% 1009 mb
Low level cloud: 0%
Mid level cloud: 48%
High level cloud: 57%
Most Significant Cloud Type: medium
50%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
18:00

WSW
WSW

5 / 5 mph 62 / 62°F 80% 1009 mb
Low level cloud: 0%
Mid level cloud: 98%
High level cloud: 100%
Most Significant Cloud Type: medium
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
21:00

W
W

6 / 10 mph 58 / 57°F 82% 1010 mb
Low level cloud: 12%
Mid level cloud: 45%
High level cloud: 91%
Most Significant Cloud Type: medium
82%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
Wed 22
May
00:00

W
W

6 / 9 mph 58 / 57°F 86% 1010 mb
Low level cloud: 17%
Mid level cloud: 42%
High level cloud: 15%
Most Significant Cloud Type: low
34%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
03:00

WNW
WNW

7 / 11 mph 57 / 55°F 88% 1010 mb
Low level cloud: 2%
Mid level cloud: 23%
High level cloud: 100%
Most Significant Cloud Type: medium
31%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
06:00

NW
NW

7 / 13 mph 57 / 54°F 87% 1010 mb
Low level cloud: 1%
Mid level cloud: 27%
High level cloud: 100%
Most Significant Cloud Type: medium
32%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
09:00

NW
NW

8 / 11 mph 59 / 57°F 84% 1011 mb
Low level cloud: 4%
Mid level cloud: 12%
High level cloud: 84%
Most Significant Cloud Type: medium
27%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
12:00

WNW
WNW

10 / 15 mph 63 / 62°F 76% 1011 mb
Low level cloud: 5%
Mid level cloud: 8%
High level cloud: 16%
Most Significant Cloud Type: low
9%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
15:00

WNW
WNW

11 / 14 mph 65 / 63°F 80% 1010 mb
Low level cloud: 34%
Mid level cloud: 17%
High level cloud: 15%
Most Significant Cloud Type: low
41%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
18:00

NW
NW

11 / 18 mph 62 / 62°F 87% 1011 mb
Low level cloud: 1%
Mid level cloud: 96%
High level cloud: 28%
Most Significant Cloud Type: medium
99%
Expect 0.1 In of precipitation over the past 3 hours.
0.1 In
21:00

NNE
NNE

4 / 6 mph 60 / 60°F 91% 1012 mb
Low level cloud: 11%
Mid level cloud: 100%
High level cloud: 22%
Most Significant Cloud Type: medium
100%
Expect 0.1 In of precipitation over the past 3 hours.
0.1 In
Thu 23
May
00:00

WNW
WNW

7 / 13 mph 55 / 53°F 90% 1012 mb
Low level cloud: 10%
Mid level cloud: 29%
High level cloud: 38%
Most Significant Cloud Type: low
25%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
03:00

NW
NW

9 / 16 mph 54 / 51°F 91% 1013 mb
Low level cloud: 21%
Mid level cloud: 44%
High level cloud: 93%
Most Significant Cloud Type: low
47%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
06:00

NW
NW

9 / 16 mph 54 / 49°F 90% 1014 mb
Low level cloud: 41%
Mid level cloud: 30%
High level cloud: 100%
Most Significant Cloud Type: low
63%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
09:00

NNW
NNW

10 / 16 mph 55 / 52°F 85% 1015 mb
Low level cloud: 74%
Mid level cloud: 46%
High level cloud: 77%
Most Significant Cloud Type: low
99%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
12:00

WNW
WNW

5 / 9 mph 57 / 56°F 82% 1015 mb
Low level cloud: 81%
Mid level cloud: 39%
High level cloud: 33%
Most Significant Cloud Type: low
98%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
15:00

SW
SW

9 / 13 mph 60 / 57°F 83% 1015 mb
Low level cloud: 46%
Mid level cloud: 28%
High level cloud: 7%
Most Significant Cloud Type: low
56%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
18:00

W
W

10 / 16 mph 59 / 55°F 85% 1016 mb
Low level cloud: 36%
Mid level cloud: 25%
High level cloud: 8%
Most Significant Cloud Type: low
46%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
21:00

NW
NW

10 / 13 mph 56 / 54°F 88% 1017 mb
Low level cloud: 15%
Mid level cloud: 7%
High level cloud: 1%
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
Fri 24
May
00:00

W
W

15 / 30 mph 47 / 41°F 97% 1011 mb
Low level cloud: 91%
Mid level cloud: 22%
High level cloud: 5%
Most Significant Cloud Type: low
99%
0.0 In
06:00

SSW
SSW

8 / 16 mph 54 / 52°F 97% 1013 mb
Low level cloud: 100%
Mid level cloud: 91%
High level cloud: 100%
Most Significant Cloud Type: low
100%
0.0 In
12:00

ENE
ENE

13 / 26 mph 58 / 55°F 92% 1015 mb
Low level cloud: 69%
Mid level cloud: 53%
High level cloud: 34%
Most Significant Cloud Type: low
91%
0.0 In
18:00

ESE
ESE

12 / 26 mph 58 / 56°F 89% 1018 mb
Low level cloud: 40%
Mid level cloud: 33%
High level cloud: 0%
Most Significant Cloud Type: low
51%
0.0 In
Sat 25
May
00:00

NNE
NNE

24 / 50 mph 57 / 53°F 89% 1015 mb
Low level cloud: 98%
Mid level cloud: 10%
High level cloud: 21%
Most Significant Cloud Type: low
100%
0.0 In
06:00

NW
NW

8 / 16 mph 56 / 54°F 87% 1024 mb
Low level cloud: 4%
Mid level cloud: 6%
High level cloud: 0%
Most Significant Cloud Type: low
5%
0.0 In
12:00

WSW
WSW

11 / 22 mph 54 / 51°F 67% 1023 mb
Low level cloud: 0%
Mid level cloud: 3%
High level cloud: 100%
Most Significant Cloud Type: medium
6%
0.0 In
18:00

E
E

9 / 19 mph 60 / 60°F 74% 1020 mb
Low level cloud: 0%
Mid level cloud: 5%
High level cloud: 0%
Most Significant Cloud Type: medium
5%
0.0 In
Sun 26
May
00:00

E
E

5 / 10 mph 61 / 61°F 92% 1014 mb
Low level cloud: 15%
Mid level cloud: 64%
High level cloud: 49%
Most Significant Cloud Type: medium
100%
0.0 In
06:00

ESE
ESE

13 / 27 mph 55 / 51°F 92% 1018 mb
Low level cloud: 23%
Mid level cloud: 10%
High level cloud: 72%
Most Significant Cloud Type: low
34%
0.0 In
12:00

ESE
ESE

10 / 21 mph 62 / 62°F 92% 1011 mb
Low level cloud: 19%
Mid level cloud: 78%
High level cloud: 80%
Most Significant Cloud Type: medium
100%
0.0 In
18:00

WSW
WSW

13 / 28 mph 60 / 60°F 82% 1016 mb
Low level cloud: 0%
Mid level cloud: 75%
High level cloud: 100%
Most Significant Cloud Type: medium
78%
0.0 In
Mon 27
May
00:00

NE
NE

13 / 28 mph 57 / 54°F 94% 1011 mb
Low level cloud: 81%
Mid level cloud: 95%
High level cloud: 100%
Most Significant Cloud Type: low
100%
0.1 In
06:00

WNW
WNW

14 / 29 mph 50 / 45°F 85% 1017 mb
Low level cloud: 6%
Mid level cloud: 1%
High level cloud: 0%
Most Significant Cloud Type: low
6%
0.0 In
12:00

NE
NE

16 / 34 mph 58 / 55°F 89% 1013 mb
Low level cloud: 61%
Mid level cloud: 65%
High level cloud: 2%
Most Significant Cloud Type: low
84%
0.0 In
18:00

WNW
WNW

9 / 18 mph 56 / 54°F 69% 1020 mb
Low level cloud: 4%
Mid level cloud: 18%
High level cloud: 0%
Most Significant Cloud Type: medium
28%
0.0 In
Tue 28
May
00:00

NE
NE

12 / 24 mph 56 / 53°F 94% 1013 mb
Low level cloud: 39%
Mid level cloud: 21%
High level cloud: 0%
Most Significant Cloud Type: low
46%
0.0 In
06:00

NW
NW

7 / 15 mph 50 / 47°F 75% 1023 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 0%
Most Significant Cloud Type: high
0%
0.0 In
12:00

SSE
SSE

6 / 13 mph 59 / 58°F 88% 1013 mb
Low level cloud: 18%
Mid level cloud: 24%
High level cloud: 98%
Most Significant Cloud Type: low
38%
0.0 In
18:00

WSW
WSW

13 / 28 mph 56 / 52°F 75% 1023 mb
Low level cloud: 12%
Mid level cloud: 18%
High level cloud: 0%
Most Significant Cloud Type: low
18%
0.0 In
Wed 29
May
00:00

WNW
WNW

8 / 17 mph 61 / 60°F 92% 1010 mb
Low level cloud: 19%
Mid level cloud: 17%
High level cloud: 6%
Most Significant Cloud Type: low
26%
0.0 In
06:00

WNW
WNW

7 / 15 mph 52 / 49°F 80% 1023 mb
Low level cloud: 0%
Mid level cloud: 15%
High level cloud: 15%
Most Significant Cloud Type: medium
15%
0.0 In
12:00

W
W

13 / 28 mph 62 / 62°F 86% 1010 mb
Low level cloud: 64%
Mid level cloud: 45%
High level cloud: 4%
Most Significant Cloud Type: low
80%
0.0 In
18:00

WSW
WSW

13 / 28 mph 55 / 51°F 79% 1021 mb
Low level cloud: 60%
Mid level cloud: 77%
High level cloud: 0%
Most Significant Cloud Type: low
87%
0.0 In
Thu 30
May
00:00

WNW
WNW

14 / 30 mph 51 / 47°F 74% 1012 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 5%
Most Significant Cloud Type: high
5%
0.0 In
06:00

SSW
SSW

14 / 30 mph 53 / 49°F 92% 1018 mb
Low level cloud: 100%
Mid level cloud: 45%
High level cloud: 100%
Most Significant Cloud Type: low
100%
0.0 In
12:00

WSW
WSW

18 / 38 mph 56 / 52°F 69% 1012 mb
Low level cloud: 0%
Mid level cloud: 13%
High level cloud: 6%
Most Significant Cloud Type: medium
12%
0.0 In
18:00

N
N

7 / 15 mph 58 / 57°F 80% 1019 mb
Low level cloud: 18%
Mid level cloud: 14%
High level cloud: 32%
Most Significant Cloud Type: low
26%
0.0 In
Fri 31
May
00:00

WSW
WSW

13 / 27 mph 52 / 48°F 75% 1010 mb
Low level cloud: 53%
Mid level cloud: 47%
High level cloud: 0%
Most Significant Cloud Type: low
69%
0.0 In
06:00

NNW
NNW

5 / 11 mph 57 / 56°F 78% 1022 mb
Low level cloud: 0%
Mid level cloud: 8%
High level cloud: 32%
Most Significant Cloud Type: medium
9%
0.0 In
12:00

WSW
WSW

15 / 31 mph 55 / 51°F 67% 1010 mb
Low level cloud: 0%
Mid level cloud: 8%
High level cloud: 0%
Most Significant Cloud Type: medium
7%
0.0 In
18:00

W
W

12 / 26 mph 58 / 55°F 79% 1022 mb
Low level cloud: 0%
Mid level cloud: 65%
High level cloud: 95%
Most Significant Cloud Type: medium
68%
0.0 In
Sat 01
Jun
00:00

NW
NW

15 / 31 mph 51 / 46°F 80% 1015 mb
Low level cloud: 0%
Mid level cloud: 4%
High level cloud: 0%
Most Significant Cloud Type: medium
3%
0.0 In
06:00

W
W

12 / 26 mph 54 / 51°F 87% 1022 mb
Low level cloud: 53%
Mid level cloud: 8%
High level cloud: 5%
Most Significant Cloud Type: low
56%
0.0 In
12:00

WSW
WSW

8 / 17 mph 55 / 53°F 65% 1019 mb
Low level cloud: 4%
Mid level cloud: 5%
High level cloud: 0%
Most Significant Cloud Type: low
5%
0.0 In
18:00

WSW
WSW

14 / 30 mph 58 / 55°F 92% 1024 mb
Low level cloud: 28%
Mid level cloud: 7%
High level cloud: 50%
Most Significant Cloud Type: low
36%
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