WEATHER FOR BUSINESS

We supply weather data to businesses

Free Weather Plugin

Add this forecast to your website



Local Weather

Feather River Marysville 14 Day Long Range Forecast

14 Day weather providing an extended long range forecast outlook for Feather River Marysville

California, United States Of America

Long range weather outlook for Feather River Marysville includes 14 day forecast summary:

Taking a look at Feather River Marysville over the coming two weeks and the average daytime maximum temperature will be around 25°C, with a high for the two weeks of 29°C expected on the afternoon of Thursday 19th. The average minimum temperature will be 13°C, dipping to its lowest on the morning of Thursday 12th at 9°C. Expect the next 14 days remain predominantly dry. On the whole winds are likely to be light.

DayLocal TimeDirSpeed/
Gust
Temp/
Feels Like
HumidityPressureCloud AmountPrecip AmountWeather
Wed 11
Mar
01:00

NNW
NNW

5 / 11 mph 49 / 47°F 58% 1025 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
04:00

NNW
NNW

5 / 11 mph 49 / 47°F 62% 1025 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
07:00

NNW
NNW

6 / 12 mph 46 / 43°F 69% 1027 mb
Low level cloud: 0%
Mid level cloud: 1%
High level cloud: 0%
Most Significant Cloud Type: medium
1%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
10:00

NW
NW

6 / 7 mph 61 / 60°F 55% 1028 mb
Low level cloud: 0%
Mid level cloud: 2%
High level cloud: 0%
Most Significant Cloud Type: medium
1%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
13:00

NW
NW

6 / 7 mph 69 / 68°F 46% 1028 mb
Low level cloud: 0%
Mid level cloud: 2%
High level cloud: 13%
Most Significant Cloud Type: medium
2%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
16:00

N
N

3 / 4 mph 72 / 76°F 47% 1026 mb
Low level cloud: 0%
Mid level cloud: 1%
High level cloud: 2%
Most Significant Cloud Type: high
1%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
19:00

NNE
NNE

3 / 6 mph 60 / 60°F 65% 1026 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 11%
Most Significant Cloud Type: high
11%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
22:00

N
N

3 / 5 mph 56 / 57°F 71% 1027 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 9%
Most Significant Cloud Type: high
9%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
Thu 12
Mar
19:00

E
E

2 / 4 mph 61 / 61°F 73% 1021 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 14%
Most Significant Cloud Type: high
14%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
22:00

ENE
ENE

2 / 4 mph 57 / 59°F 79% 1021 mb
Low level cloud: 0%
Mid level cloud: 1%
High level cloud: 20%
Most Significant Cloud Type: high
20%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
Fri 13
Mar
01:00

NE
NE

2 / 3 mph 56 / 56°F 80% 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
04:00

NNW
NNW

3 / 6 mph 52 / 52°F 82% 1020 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 89%
Most Significant Cloud Type: high
89%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
07:00

NNW
NNW

2 / 4 mph 53 / 53°F 82% 1020 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 32%
Most Significant Cloud Type: high
31%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
10:00

NNW
NNW

4 / 4 mph 66 / 64°F 64% 1019 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 32%
Most Significant Cloud Type: high
31%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
13:00

NW
NW

4 / 4 mph 71 / 70°F 55% 1018 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 100%
Most Significant Cloud Type: high
99%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
16:00

SSE
SSE

2 / 2 mph 74 / 76°F 55% 1015 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 34%
Most Significant Cloud Type: high
34%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
19:00

SE
SE

3 / 7 mph 60 / 60°F 78% 1015 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 94%
Most Significant Cloud Type: high
94%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
22:00

ESE
ESE

3 / 6 mph 57 / 58°F 84% 1015 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 64%
Most Significant Cloud Type: high
63%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
Sat 14
Mar
01:00

ESE
ESE

2 / 5 mph 56 / 57°F 85% 1016 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 13%
Most Significant Cloud Type: high
12%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
04:00

ENE
ENE

1 / 2 mph 54 / 54°F 85% 1015 mb
Low level cloud: 0%
Mid level cloud: 4%
High level cloud: 97%
Most Significant Cloud Type: medium
7%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
07:00

N
N

2 / 4 mph 54 / 53°F 85% 1017 mb
Low level cloud: 0%
Mid level cloud: 4%
High level cloud: 1%
Most Significant Cloud Type: medium
3%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
10:00

NW
NW

6 / 7 mph 66 / 64°F 69% 1017 mb
Low level cloud: 0%
Mid level cloud: 3%
High level cloud: 6%
Most Significant Cloud Type: medium
2%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
13:00

NW
NW

9 / 11 mph 73 / 76°F 52% 1017 mb
Low level cloud: 0%
Mid level cloud: 3%
High level cloud: 19%
Most Significant Cloud Type: medium
3%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
16:00

NW
NW

7 / 10 mph 75 / 77°F 55% 1015 mb
Low level cloud: 0%
Mid level cloud: 3%
High level cloud: 0%
Most Significant Cloud Type: medium
2%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
19:00

NNW
NNW

5 / 10 mph 66 / 66°F 74% 1016 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
22:00

NNW
NNW

4 / 9 mph 59 / 59°F 84% 1017 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 3%
Most Significant Cloud Type: high
2%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
Sun 15
Mar
01:00

NNW
NNW

6 / 12 mph 55 / 54°F 83% 1017 mb
Low level cloud: 0%
Mid level cloud: 1%
High level cloud: 5%
Most Significant Cloud Type: high
5%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
04:00

NNW
NNW

6 / 12 mph 53 / 51°F 74% 1017 mb
Low level cloud: 0%
Mid level cloud: 3%
High level cloud: 0%
Most Significant Cloud Type: medium
2%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
07:00

NNW
NNW

6 / 14 mph 52 / 48°F 66% 1018 mb
Low level cloud: 0%
Mid level cloud: 3%
High level cloud: 0%
Most Significant Cloud Type: medium
3%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
10:00

NW
NW

9 / 12 mph 65 / 64°F 49% 1018 mb
Low level cloud: 0%
Mid level cloud: 3%
High level cloud: 1%
Most Significant Cloud Type: medium
2%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
13:00

NW
NW

11 / 14 mph 75 / 76°F 41% 1017 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 4%
Most Significant Cloud Type: high
3%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
16:00

NNW
NNW

9 / 14 mph 77 / 77°F 52% 1015 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 8%
Most Significant Cloud Type: high
7%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
19:00

NNW
NNW

4 / 9 mph 67 / 67°F 67% 1016 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 1%
Most Significant Cloud Type: high
1%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
22:00

N
N

4 / 9 mph 60 / 60°F 67% 1017 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 32%
Most Significant Cloud Type: high
32%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
Mon 16
Mar
01:00

NNW
NNW

4 / 10 mph 59 / 59°F 61% 1017 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
04:00

NNW
NNW

4 / 9 mph 57 / 57°F 62% 1016 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
07:00

NNW
NNW

3 / 6 mph 56 / 55°F 67% 1018 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
10:00

NW
NW

5 / 6 mph 71 / 69°F 54% 1018 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
13:00

NW
NW

8 / 10 mph 82 / 81°F 46% 1015 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
16:00

NNW
NNW

9 / 14 mph 82 / 82°F 55% 1012 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
19:00

NNW
NNW

2 / 5 mph 74 / 77°F 66% 1013 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
22:00

SE
SE

3 / 6 mph 67 / 67°F 77% 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
Tue 17
Mar
01:00

SE
SE

4 / 9 mph 62 / 62°F 83% 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
04:00

SE
SE

1 / 2 mph 59 / 59°F 81% 1015 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
07:00

ESE
ESE

1 / 2 mph 59 / 58°F 79% 1016 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
10:00

NNW
NNW

1 / 1 mph 74 / 76°F 62% 1016 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
13:00

W
W

1 / 1 mph 82 / 81°F 49% 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
16:00

ESE
ESE

2 / 2 mph 83 / 82°F 50% 1013 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
19:00

ESE
ESE

2 / 3 mph 76 / 79°F 74% 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
22:00

ENE
ENE

2 / 5 mph 68 / 68°F 80% 1015 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
DayLocal TimeDirSpeed/
Gust
Temp/
Feels Like
HumidityPressureCloud AmountPrecip AmountWeather
Wed 18
Mar
04:00

NNW
NNW

5 / 10 mph 62 / 62°F 84% 1014 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 0%
Most Significant Cloud Type: high
0%
0.0 In
10:00

NW
NW

4 / 5 mph 73 / 77°F 66% 1014 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 7%
Most Significant Cloud Type: high
6%
0.0 In
16:00

SSE
SSE

6 / 6 mph 83 / 86°F 56% 1013 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 0%
Most Significant Cloud Type: high
0%
0.0 In
22:00

E
E

3 / 6 mph 68 / 68°F 79% 1015 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 0%
Most Significant Cloud Type: high
0%
0.0 In
Thu 19
Mar
04:00

ENE
ENE

2 / 4 mph 63 / 63°F 81% 1015 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 3%
Most Significant Cloud Type: high
3%
0.0 In
10:00

NNW
NNW

3 / 4 mph 75 / 78°F 63% 1017 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 0%
Most Significant Cloud Type: high
0%
0.0 In
16:00

SSE
SSE

9 / 11 mph 78 / 80°F 53% 1015 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 0%
Most Significant Cloud Type: high
0%
0.0 In
22:00

SE
SE

6 / 13 mph 65 / 65°F 77% 1016 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 0%
Most Significant Cloud Type: high
0%
0.0 In
Fri 20
Mar
04:00

SSE
SSE

8 / 16 mph 52 / 49°F 69% 1016 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 0%
Most Significant Cloud Type: high
0%
0.0 In
10:00

SW
SW

2 / 2 mph 73 / 77°F 55% 1017 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 22%
Most Significant Cloud Type: high
21%
0.0 In
16:00

SSE
SSE

5 / 6 mph 74 / 77°F 55% 1014 mb
Low level cloud: 0%
Mid level cloud: 4%
High level cloud: 10%
Most Significant Cloud Type: medium
4%
0.0 In
22:00

SE
SE

6 / 12 mph 63 / 63°F 76% 1014 mb
Low level cloud: 0%
Mid level cloud: 4%
High level cloud: 13%
Most Significant Cloud Type: medium
4%
0.0 In
Sat 21
Mar
04:00

NW
NW

11 / 20 mph 45 / 40°F 48% 1020 mb
Low level cloud: 0%
Mid level cloud: 6%
High level cloud: 0%
Most Significant Cloud Type: medium
5%
0.0 In
10:00

NW
NW

11 / 13 mph 59 / 59°F 57% 1018 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 32%
Most Significant Cloud Type: high
31%
0.0 In
16:00

NNW
NNW

6 / 8 mph 58 / 57°F 39% 1019 mb
Low level cloud: 0%
Mid level cloud: 53%
High level cloud: 0%
Most Significant Cloud Type: medium
52%
0.0 In
22:00

NW
NW

7 / 15 mph 48 / 44°F 47% 1017 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 0%
Most Significant Cloud Type: high
0%
0.0 In
Sun 22
Mar
04:00

NNW
NNW

5 / 10 mph 36 / 31°F 63% 1023 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 0%
Most Significant Cloud Type: high
0%
0.0 In
10:00

NW
NW

11 / 13 mph 54 / 51°F 44% 1020 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 0%
Most Significant Cloud Type: high
0%
0.0 In
16:00

NNW
NNW

13 / 17 mph 56 / 52°F 34% 1020 mb
Low level cloud: 0%
Mid level cloud: 2%
High level cloud: 0%
Most Significant Cloud Type: medium
1%
0.0 In
22:00

N
N

3 / 6 mph 51 / 51°F 49% 1018 mb
Low level cloud: 0%
Mid level cloud: 15%
High level cloud: 72%
Most Significant Cloud Type: medium
17%
0.0 In
Mon 23
Mar
04:00

NNW
NNW

10 / 21 mph 36 / 28°F 55% 1021 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 32%
Most Significant Cloud Type: high
32%
0.0 In
10:00

NW
NW

9 / 10 mph 55 / 52°F 44% 1018 mb
Low level cloud: 0%
Mid level cloud: 6%
High level cloud: 5%
Most Significant Cloud Type: medium
6%
0.0 In
16:00

NW
NW

17 / 24 mph 57 / 54°F 37% 1018 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 4%
Most Significant Cloud Type: high
4%
0.0 In
22:00

NNE
NNE

2 / 5 mph 52 / 53°F 55% 1016 mb
Low level cloud: 0%
Mid level cloud: 3%
High level cloud: 4%
Most Significant Cloud Type: medium
2%
0.0 In
Tue 24
Mar
04:00

NNW
NNW

6 / 12 mph 36 / 31°F 51% 1020 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 1%
Most Significant Cloud Type: high
1%
0.0 In
10:00

WNW
WNW

4 / 5 mph 60 / 60°F 48% 1019 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 0%
Most Significant Cloud Type: high
0%
0.0 In
16:00

SSE
SSE

4 / 5 mph 66 / 66°F 35% 1020 mb
Low level cloud: 0%
Mid level cloud: 1%
High level cloud: 22%
Most Significant Cloud Type: high
22%
0.0 In
22:00

E
E

2 / 5 mph 57 / 58°F 68% 1018 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 1%
Most Significant Cloud Type: high
1%
0.0 In
Wed 25
Mar
04:00

NNW
NNW

3 / 6 mph 48 / 47°F 59% 1023 mb
Low level cloud: 0%
Mid level cloud: 5%
High level cloud: 100%
Most Significant Cloud Type: medium
9%
0.0 In
10:00

SSE
SSE

6 / 7 mph 60 / 60°F 62% 1017 mb
Low level cloud: 0%
Mid level cloud: 59%
High level cloud: 100%
Most Significant Cloud Type: medium
62%
0.0 In
16:00

NNW
NNW

2 / 3 mph 66 / 66°F 53% 1019 mb
Low level cloud: 0%
Mid level cloud: 58%
High level cloud: 100%
Most Significant Cloud Type: medium
61%
0.0 In
22:00

SE
SE

8 / 17 mph 49 / 46°F 87% 1016 mb
Low level cloud: 0%
Mid level cloud: 0%
High level cloud: 5%
Most Significant Cloud Type: high
4%
0.0 In
Thu 26
Mar
04:00

NW
NW

4 / 8 mph 53 / 52°F 62% 1017 mb
Low level cloud: 0%
Mid level cloud: 99%
High level cloud: 87%
Most Significant Cloud Type: medium
100%
0.0 In
10:00

S
S

10 / 12 mph 59 / 57°F 72% 1017 mb
Low level cloud: 29%
Mid level cloud: 36%
High level cloud: 100%
Most Significant Cloud Type: low
53%
0.0 In
16:00

N
N

4 / 5 mph 73 / 76°F 44% 1013 mb
Low level cloud: 0%
Mid level cloud: 30%
High level cloud: 32%
Most Significant Cloud Type: medium
31%
0.0 In
22:00

SSE
SSE

9 / 17 mph 51 / 47°F 95% 1015 mb
Low level cloud: 11%
Mid level cloud: 8%
High level cloud: 33%
Most Significant Cloud Type: low
18%
0.1 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