Fast Forecast

WEATHER FOR BUSINESS

We supply weather data to businesses

Free Weather Plugin

Add this forecast to your website



Local Weather

Tambo Grande 14 Day Long Range Forecast

14 Day weather providing an extended long range forecast outlook for Tambo Grande

Peru

Long range weather outlook for Tambo Grande includes 14 day forecast summary:

Over the next 14 days the Tambo Grande forecast suggests the average daytime maximum temperature will be around 33°C, with a high for the two weeks of 35°C expected on the afternoon of Sunday 5th. The mean minimum temperature will be 22°C, dipping to its lowest on the morning of Friday 10th at 21°C. The next 14 days will have mixed weather with some days dry and some seeing a little rain. The indicators are that Thursday 9th will have the most precipitation with an accumulation of around 1.0mm. On the whole winds are likely to be moderate.

DayLocal TimeDirSpeed/
Gust		Temp/
Feels Like		HumidityPressureCloud AmountPrecip AmountWeather
Fri 03
May		01:00

S
S

 6 / 6 mph 76 / 78°F 68% 1011 mb
Low level cloud: 1%
Mid level cloud: 44%
High level cloud: 0%
Most Significant Cloud Type: medium
47%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
04:00

S
S

 4 / 5 mph 74 / 77°F 72% 1010 mb
Low level cloud: 4%
Mid level cloud: 29%
High level cloud: 0%
Most Significant Cloud Type: medium
39%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
07:00

S
S

 5 / 6 mph 75 / 77°F 72% 1011 mb
Low level cloud: 8%
Mid level cloud: 57%
High level cloud: 0%
Most Significant Cloud Type: medium
78%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
10:00

SW
SW

 4 / 4 mph 83 / 82°F 59% 1012 mb
Low level cloud: 3%
Mid level cloud: 49%
High level cloud: 0%
Most Significant Cloud Type: medium
57%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
13:00

SW
SW

 5 / 6 mph 89 / 89°F 47% 1009 mb
Low level cloud: 0%
Mid level cloud: 44%
High level cloud: 0%
Most Significant Cloud Type: medium
44%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
16:00

SSW
SSW

 6 / 7 mph 90 / 90°F 45% 1006 mb
Low level cloud: 1%
Mid level cloud: 44%
High level cloud: 0%
Most Significant Cloud Type: medium
46%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
19:00

SSW
SSW

 9 / 12 mph 83 / 85°F 51% 1008 mb
Low level cloud: 0%
Mid level cloud: 53%
High level cloud: 0%
Most Significant Cloud Type: medium
54%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
22:00

S
S

 10 / 12 mph 76 / 79°F 64% 1011 mb
Low level cloud: 0%
Mid level cloud: 54%
High level cloud: 0%
Most Significant Cloud Type: medium
54%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
Sat 04
May		22:00

S
S

 10 / 12 mph 77 / 80°F 61% 1011 mb
Low level cloud: 0%
Mid level cloud: 44%
High level cloud: 3%
Most Significant Cloud Type: medium
44%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
Sun 05
May		01:00

S
S

 6 / 8 mph 75 / 78°F 67% 1012 mb
Low level cloud: 15%
Mid level cloud: 45%
High level cloud: 3%
Most Significant Cloud Type: medium
86%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
04:00

SSE
SSE

 3 / 4 mph 73 / 77°F 71% 1011 mb
Low level cloud: 31%
Mid level cloud: 44%
High level cloud: 1%
Most Significant Cloud Type: low
46%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
07:00

SSE
SSE

 4 / 5 mph 76 / 77°F 71% 1012 mb
Low level cloud: 5%
Mid level cloud: 22%
High level cloud: 4%
Most Significant Cloud Type: medium
35%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
10:00

SSE
SSE

 1 / 1 mph 86 / 85°F 52% 1011 mb
Low level cloud: 0%
Mid level cloud: 21%
High level cloud: 2%
Most Significant Cloud Type: medium
20%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
13:00

SW
SW

 8 / 9 mph 94 / 96°F 40% 1008 mb
Low level cloud: 0%
Mid level cloud: 18%
High level cloud: 7%
Most Significant Cloud Type: medium
18%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
16:00

SSW
SSW

 12 / 14 mph 95 / 97°F 38% 1006 mb
Low level cloud: 0%
Mid level cloud: 29%
High level cloud: 0%
Most Significant Cloud Type: medium
28%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
19:00

SW
SW

 14 / 18 mph 83 / 85°F 50% 1009 mb
Low level cloud: 0%
Mid level cloud: 45%
High level cloud: 0%
Most Significant Cloud Type: medium
44%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
22:00

S
S

 10 / 12 mph 77 / 80°F 62% 1013 mb
Low level cloud: 2%
Mid level cloud: 45%
High level cloud: 4%
Most Significant Cloud Type: medium
49%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
Mon 06
May		01:00

SSE
SSE

 7 / 9 mph 74 / 77°F 71% 1012 mb
Low level cloud: 9%
Mid level cloud: 46%
High level cloud: 88%
Most Significant Cloud Type: medium
73%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
04:00

SSE
SSE

 5 / 6 mph 73 / 77°F 76% 1011 mb
Low level cloud: 7%
Mid level cloud: 47%
High level cloud: 99%
Most Significant Cloud Type: medium
72%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
07:00

SSE
SSE

 3 / 3 mph 76 / 76°F 77% 1011 mb
Low level cloud: 3%
Mid level cloud: 47%
High level cloud: 85%
Most Significant Cloud Type: medium
59%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
10:00

SW
SW

 2 / 3 mph 80 / 80°F 66% 1012 mb
Low level cloud: 2%
Mid level cloud: 44%
High level cloud: 49%
Most Significant Cloud Type: medium
52%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
13:00

WSW
WSW

 3 / 3 mph 86 / 85°F 54% 1010 mb
Low level cloud: 16%
Mid level cloud: 39%
High level cloud: 33%
Most Significant Cloud Type: low
33%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
16:00

SSW
SSW

 7 / 8 mph 89 / 91°F 44% 1007 mb
Low level cloud: 16%
Mid level cloud: 55%
High level cloud: 21%
Most Significant Cloud Type: medium
100%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
19:00

S
S

 11 / 14 mph 83 / 85°F 52% 1009 mb
Low level cloud: 6%
Mid level cloud: 46%
High level cloud: 28%
Most Significant Cloud Type: medium
62%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
22:00

S
S

 11 / 13 mph 77 / 80°F 60% 1012 mb
Low level cloud: 4%
Mid level cloud: 51%
High level cloud: 33%
Most Significant Cloud Type: medium
63%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
Tue 07
May		01:00

S
S

 8 / 9 mph 75 / 78°F 67% 1012 mb
Low level cloud: 2%
Mid level cloud: 75%
High level cloud: 32%
Most Significant Cloud Type: medium
82%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
04:00

S
S

 6 / 6 mph 73 / 77°F 70% 1011 mb
Low level cloud: 3%
Mid level cloud: 46%
High level cloud: 22%
Most Significant Cloud Type: medium
55%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
07:00

S
S

 5 / 6 mph 74 / 77°F 71% 1012 mb
Low level cloud: 5%
Mid level cloud: 83%
High level cloud: 8%
Most Significant Cloud Type: medium
97%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
10:00

S
S

 3 / 4 mph 81 / 80°F 60% 1013 mb
Low level cloud: 0%
Mid level cloud: 44%
High level cloud: 0%
Most Significant Cloud Type: medium
45%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
13:00

SW
SW

 9 / 10 mph 91 / 92°F 42% 1010 mb
Low level cloud: 4%
Mid level cloud: 32%
High level cloud: 0%
Most Significant Cloud Type: medium
43%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
16:00

SSW
SSW

 12 / 13 mph 93 / 94°F 39% 1007 mb
Low level cloud: 0%
Mid level cloud: 46%
High level cloud: 0%
Most Significant Cloud Type: medium
46%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
19:00

SSW
SSW

 12 / 16 mph 84 / 85°F 47% 1008 mb
Low level cloud: 0%
Mid level cloud: 44%
High level cloud: 2%
Most Significant Cloud Type: medium
43%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
22:00

S
S

 11 / 13 mph 76 / 79°F 60% 1012 mb
Low level cloud: 0%
Mid level cloud: 81%
High level cloud: 7%
Most Significant Cloud Type: medium
81%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
Wed 08
May		01:00

S
S

 5 / 6 mph 75 / 78°F 64% 1011 mb
Low level cloud: 0%
Mid level cloud: 44%
High level cloud: 16%
Most Significant Cloud Type: medium
44%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
04:00

SSW
SSW

 4 / 5 mph 74 / 77°F 66% 1010 mb
Low level cloud: 0%
Mid level cloud: 46%
High level cloud: 9%
Most Significant Cloud Type: medium
46%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
07:00

S
S

 8 / 9 mph 75 / 76°F 70% 1011 mb
Low level cloud: 5%
Mid level cloud: 38%
High level cloud: 10%
Most Significant Cloud Type: medium
51%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
10:00

SSW
SSW

 4 / 5 mph 83 / 82°F 54% 1012 mb
Low level cloud: 11%
Mid level cloud: 15%
High level cloud: 0%
Most Significant Cloud Type: low
15%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
13:00

SW
SW

 7 / 9 mph 91 / 91°F 41% 1009 mb
Low level cloud: 3%
Mid level cloud: 30%
High level cloud: 3%
Most Significant Cloud Type: medium
39%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
16:00

SW
SW

 11 / 12 mph 92 / 93°F 39% 1007 mb
Low level cloud: 0%
Mid level cloud: 66%
High level cloud: 8%
Most Significant Cloud Type: medium
66%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
19:00

SSW
SSW

 14 / 17 mph 83 / 84°F 48% 1009 mb
Low level cloud: 0%
Mid level cloud: 45%
High level cloud: 12%
Most Significant Cloud Type: medium
45%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
22:00

S
S

 8 / 9 mph 77 / 79°F 61% 1012 mb
Low level cloud: 0%
Mid level cloud: 46%
High level cloud: 15%
Most Significant Cloud Type: medium
46%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
Thu 09
May		01:00

SSE
SSE

 4 / 4 mph 75 / 78°F 69% 1011 mb
Low level cloud: 0%
Mid level cloud: 47%
High level cloud: 7%
Most Significant Cloud Type: medium
47%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
04:00

SSE
SSE

 4 / 4 mph 74 / 77°F 74% 1011 mb
Low level cloud: 0%
Mid level cloud: 44%
High level cloud: 31%
Most Significant Cloud Type: medium
45%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
07:00

S
S

 3 / 3 mph 76 / 77°F 75% 1012 mb
Low level cloud: 1%
Mid level cloud: 51%
High level cloud: 21%
Most Significant Cloud Type: medium
54%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
10:00

S
S

 3 / 4 mph 78 / 78°F 70% 1013 mb
Low level cloud: 3%
Mid level cloud: 44%
High level cloud: 17%
Most Significant Cloud Type: medium
53%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
13:00

S
S

 3 / 4 mph 80 / 80°F 66% 1010 mb
Low level cloud: 2%
Mid level cloud: 44%
High level cloud: 14%
Most Significant Cloud Type: medium
49%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
16:00

SSW
SSW

 8 / 9 mph 84 / 84°F 57% 1009 mb
Low level cloud: 1%
Mid level cloud: 48%
High level cloud: 16%
Most Significant Cloud Type: medium
50%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
19:00

SSW
SSW

 11 / 15 mph 78 / 80°F 60% 1011 mb
Low level cloud: 24%
Mid level cloud: 46%
High level cloud: 7%
Most Significant Cloud Type: low
41%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
22:00

S
S

 8 / 10 mph 73 / 77°F 69% 1013 mb
Low level cloud: 5%
Mid level cloud: 33%
High level cloud: 32%
Most Significant Cloud Type: medium
48%
Expect 0.0 In of precipitation over the past 3 hours.
0.0 In
DayLocal TimeDirSpeed/
Gust		Temp/
Feels Like		HumidityPressureCloud AmountPrecip AmountWeather
Fri 10
May		01:00

SSE
SSE

 4 / 7 mph 73 / 77°F 73% 1013 mb
Low level cloud: 7%
Mid level cloud: 32%
High level cloud: 17%
Most Significant Cloud Type: medium
50%
0.0 In
07:00

S
S

 5 / 8 mph 73 / 77°F 74% 1013 mb
Low level cloud: 15%
Mid level cloud: 48%
High level cloud: 16%
Most Significant Cloud Type: medium
89%
0.0 In
13:00

SSW
SSW

 8 / 12 mph 90 / 92°F 41% 1009 mb
Low level cloud: 0%
Mid level cloud: 22%
High level cloud: 21%
Most Significant Cloud Type: medium
23%
0.0 In
19:00

S
S

 12 / 17 mph 79 / 81°F 56% 1009 mb
Low level cloud: 0%
Mid level cloud: 45%
High level cloud: 62%
Most Significant Cloud Type: medium
46%
0.0 In
Sat 11
May		01:00

S
S

 4 / 5 mph 77 / 80°F 70% 1011 mb
Low level cloud: 0%
Mid level cloud: 22%
High level cloud: 22%
Most Significant Cloud Type: medium
22%
0.0 In
07:00

SSW
SSW

 4 / 6 mph 73 / 77°F 72% 1011 mb
Low level cloud: 0%
Mid level cloud: 46%
High level cloud: 10%
Most Significant Cloud Type: medium
47%
0.0 In
13:00

SW
SW

 6 / 9 mph 91 / 93°F 41% 1009 mb
Low level cloud: 0%
Mid level cloud: 14%
High level cloud: 12%
Most Significant Cloud Type: medium
14%
0.0 In
19:00

SSW
SSW

 14 / 20 mph 81 / 83°F 52% 1010 mb
Low level cloud: 0%
Mid level cloud: 23%
High level cloud: 0%
Most Significant Cloud Type: medium
22%
0.0 In
Sun 12
May		01:00

S
S

 7 / 12 mph 73 / 77°F 68% 1013 mb
Low level cloud: 0%
Mid level cloud: 21%
High level cloud: 7%
Most Significant Cloud Type: medium
21%
0.0 In
07:00

S
S

 5 / 7 mph 72 / 76°F 73% 1013 mb
Low level cloud: 2%
Mid level cloud: 23%
High level cloud: 0%
Most Significant Cloud Type: medium
29%
0.0 In
13:00

SSW
SSW

 6 / 11 mph 88 / 91°F 43% 1010 mb
Low level cloud: 0%
Mid level cloud: 26%
High level cloud: 1%
Most Significant Cloud Type: medium
25%
0.0 In
19:00

SSW
SSW

 13 / 20 mph 81 / 82°F 52% 1009 mb
Low level cloud: 0%
Mid level cloud: 22%
High level cloud: 3%
Most Significant Cloud Type: medium
21%
0.0 In
Mon 13
May		01:00

SSE
SSE

 6 / 11 mph 72 / 76°F 70% 1013 mb
Low level cloud: 6%
Mid level cloud: 44%
High level cloud: 58%
Most Significant Cloud Type: medium
61%
0.0 In
07:00

SSE
SSE

 4 / 6 mph 72 / 76°F 74% 1013 mb
Low level cloud: 5%
Mid level cloud: 23%
High level cloud: 37%
Most Significant Cloud Type: medium
38%
0.0 In
13:00

SSW
SSW

 7 / 12 mph 90 / 92°F 40% 1010 mb
Low level cloud: 1%
Mid level cloud: 19%
High level cloud: 9%
Most Significant Cloud Type: medium
23%
0.0 In
19:00

S
S

 16 / 24 mph 79 / 80°F 56% 1010 mb
Low level cloud: 0%
Mid level cloud: 16%
High level cloud: 16%
Most Significant Cloud Type: medium
17%
0.0 In
Tue 14
May		01:00

S
S

 3 / 6 mph 75 / 78°F 71% 1014 mb
Low level cloud: 0%
Mid level cloud: 46%
High level cloud: 19%
Most Significant Cloud Type: medium
47%
0.0 In
07:00

S
S

 5 / 7 mph 73 / 77°F 73% 1012 mb
Low level cloud: 1%
Mid level cloud: 19%
High level cloud: 6%
Most Significant Cloud Type: medium
22%
0.0 In
13:00

SSW
SSW

 8 / 14 mph 89 / 91°F 41% 1011 mb
Low level cloud: 0%
Mid level cloud: 20%
High level cloud: 1%
Most Significant Cloud Type: medium
21%
0.0 In
19:00

S
S

 15 / 23 mph 80 / 82°F 53% 1010 mb
Low level cloud: 0%
Mid level cloud: 29%
High level cloud: 0%
Most Significant Cloud Type: medium
28%
0.0 In
Wed 15
May		01:00

S
S

 4 / 8 mph 72 / 76°F 75% 1014 mb
Low level cloud: 10%
Mid level cloud: 30%
High level cloud: 36%
Most Significant Cloud Type: medium
59%
0.0 In
07:00

SSW
SSW

 3 / 4 mph 74 / 78°F 71% 1013 mb
Low level cloud: 1%
Mid level cloud: 23%
High level cloud: 11%
Most Significant Cloud Type: medium
25%
0.0 In
13:00

SW
SW

 7 / 13 mph 88 / 90°F 44% 1011 mb
Low level cloud: 0%
Mid level cloud: 14%
High level cloud: 9%
Most Significant Cloud Type: medium
13%
0.0 In
19:00

S
S

 16 / 24 mph 79 / 80°F 55% 1010 mb
Low level cloud: 0%
Mid level cloud: 26%
High level cloud: 0%
Most Significant Cloud Type: medium
25%
0.0 In
Thu 16
May		01:00

SSE
SSE

 5 / 9 mph 75 / 78°F 70% 1012 mb
Low level cloud: 2%
Mid level cloud: 18%
High level cloud: 9%
Most Significant Cloud Type: medium
24%
0.0 In
07:00

S
S

 3 / 4 mph 74 / 78°F 74% 1012 mb
Low level cloud: 3%
Mid level cloud: 16%
High level cloud: 0%
Most Significant Cloud Type: medium
23%
0.0 In
13:00

SW
SW

 7 / 13 mph 90 / 92°F 41% 1009 mb
Low level cloud: 0%
Mid level cloud: 24%
High level cloud: 0%
Most Significant Cloud Type: medium
24%
0.0 In
19:00

SSW
SSW

 14 / 21 mph 81 / 83°F 50% 1010 mb
Low level cloud: 0%
Mid level cloud: 21%
High level cloud: 1%
Most Significant Cloud Type: medium
21%
0.0 In
Fri 17
May		01:00

S
S

 6 / 11 mph 75 / 78°F 67% 1012 mb
Low level cloud: 0%
Mid level cloud: 23%
High level cloud: 39%
Most Significant Cloud Type: medium
24%
0.0 In
07:00

SSE
SSE

 3 / 4 mph 73 / 77°F 75% 1012 mb
Low level cloud: 2%
Mid level cloud: 19%
High level cloud: 0%
Most Significant Cloud Type: medium
25%
0.0 In
13:00

SW
SW

 6 / 12 mph 91 / 93°F 40% 1008 mb
Low level cloud: 0%
Mid level cloud: 14%
High level cloud: 32%
Most Significant Cloud Type: medium
15%
0.0 In
19:00

SSW
SSW

 15 / 22 mph 81 / 83°F 51% 1009 mb
Low level cloud: 0%
Mid level cloud: 16%
High level cloud: 32%
Most Significant Cloud Type: medium
16%
0.0 In
Sat 18
May		01:00

S
S

 6 / 11 mph 73 / 77°F 72% 1012 mb
Low level cloud: 10%
Mid level cloud: 21%
High level cloud: 36%
Most Significant Cloud Type: low
21%
0.0 In
07:00

S
S

 4 / 6 mph 72 / 76°F 76% 1013 mb
Low level cloud: 4%
Mid level cloud: 23%
High level cloud: 6%
Most Significant Cloud Type: medium
34%
0.0 In
13:00

SW
SW

 8 / 15 mph 89 / 91°F 41% 1008 mb
Low level cloud: 0%
Mid level cloud: 14%
High level cloud: 5%
Most Significant Cloud Type: medium
13%
0.0 In
19:00

SW
SW

 13 / 21 mph 80 / 81°F 55% 1010 mb
Low level cloud: 0%
Mid level cloud: 45%
High level cloud: 98%
Most Significant Cloud Type: medium
48%
0.0 In

Other Locations Near to Tambo Grande

Cities and Towns: Chulucanas, Peru

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