Cameron
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cameron clear sky chart from 2005-11-05 to 2018-02-14.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.
Observation TypeMinimum conditions for hour to be usableOut of hours
Clear of CloudsTransparencySeeingSky Brightness
Planetary:50%(no limit)Average(no limit)Nighttime Hours
Deep Sky:70%Average(no limit)5.9Nighttime Hours
CCD Imaging:70%Below AveragePoor(no limit)Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

PlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
Night
40%
16604
22%
48866
13%
16557
49%
16557
30%
29791

By Month

MonthDays of MonthPlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
January1st to 15thNight
28%
975
22%
2532
8%
970
39%
970
31%
1603
January16th to endNight
26%
1040
23%
2704
7%
1040
37%
1040
30%
1760
February1st to 15thNight
25%
950
14%
2470
5%
946
31%
946
22%
1770
February16th to endNight
27%
687
23%
1949
6%
687
39%
687
30%
1219
March1st to 15thNight
32%
540
21%
1980
12%
540
44%
540
23%
1173
March16th to endNight
25%
576
14%
2112
9%
576
33%
576
17%
1416
April1st to 15thNight
33%
539
20%
1833
13%
539
45%
539
27%
1072
April16th to endNight
31%
540
21%
1720
13%
540
44%
540
23%
1111
May1st to 15thNight
38%
539
19%
1620
13%
539
46%
539
24%
1076
May16th to endNight
45%
563
20%
1568
12%
561
53%
561
33%
974
June1st to 15thNight
60%
540
19%
1440
10%
540
64%
540
41%
846
June16th to endNight
60%
540
23%
1440
13%
540
65%
540
49%
803
July1st to 15thNight
68%
510
19%
1443
13%
510
70%
510
43%
799
July16th to endNight
74%
564
24%
1594
23%
531
77%
531
45%
831
August1st to 15thNight
76%
539
24%
1610
26%
536
78%
536
45%
838
August16th to endNight
69%
573
26%
1821
28%
573
72%
573
38%
993
September1st to 15thNight
64%
540
26%
1818
26%
540
69%
540
34%
1011
September16th to endNight
61%
549
29%
1992
25%
549
69%
549
36%
1020
October1st to 15thNight
43%
720
26%
2160
18%
720
49%
720
35%
1246
October16th to endNight
36%
768
29%
2304
14%
768
48%
768
34%
1321
November1st to 15thNight
39%
822
27%
2384
13%
822
50%
822
35%
1344
November16th to endNight
29%
975
23%
2730
9%
975
41%
975
31%
1680
December1st to 15thNight
29%
975
17%
2730
6%
975
37%
975
23%
1848
December16th to endNight
24%
1040
20%
2912
6%
1040
36%
1040
21%
2037

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

Occurrence of each ForecastData
Points
Cloud CoverDay
12%6%35%5%3445%7%42%
49204
Night
10%6%24424346%48%
49058
TransparencyDay
40%5%13%24%13%1
48901
Night
35%412%26%16%2
48866
SeeingDay
13%7%26%30%17%4
6394
Night
13%8%31%32%12%1
16605

By Month

Percentage Cloud Cover SE (2006-)
Color Meanings:
Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
11%6%46%6%3345%7%40%
1733
16th to endDay
11%12%37%6%34345%37%
1872
February1st to 15thDay
14%8%5%6%5%3445%6%35%
1694
16th to endDay
11%9%47%5%23346%40%
1532
March1st to 15thDay
12%11%46%5%35%446%36%
1980
16th to endDay
20%10%37%5%24345%32%
2110
April1st to 15thDay
16%7%35%5%23445%40%
2115
16th to endDay
22%7%27%5%2345%7%31%
2238
May1st to 15thDay
16%8%36%5%35%45%6%33%
2331
16th to endDay
13%6%35%5%35%46%7%39%
2544
June1st to 15thDay
8%5%25%6%345%5%8%43%
2520
16th to endDay
5%3145%35%5%7%10%47%
2520
July1st to 15thDay
8%425%435%5%6%9%45%
2426
16th to endDay
5%3245%25%5%6%9%48%
2466
August1st to 15thDay
7%425%5%25%5%6%9%45%
2340
16th to endDay
9%5%25%43436%7%46%
2381
September1st to 15thDay
11%5%23434446%50%
2139
16th to endDay
8%42342445%7%51%
1956
October1st to 15thDay
15%6%24324345%48%
1800
16th to endDay
12%5%14323245%52%
1920
November1st to 15thDay
10%5%233235%5%6%51%
1803
16th to endDay
16%7%3331335%6%44%
1560
December1st to 15thDay
12%9%36%5%33446%37%
1560
16th to endDay
13%10%48%433446%34%
1664
January1st to 15thNight
8%5%245%3445%7%47%
2532
16th to endNight
8%7%45%42345%6%45%
2704
February1st to 15thNight
11%10%47%6%34445%36%
2460
16th to endNight
11%7%3432336%6%47%
1949
March1st to 15thNight
12%6%35%424445%46%
1980
16th to endNight
20%8%35%423346%35%
2112
April1st to 15thNight
11%6%24423346%49%
1833
16th to endNight
16%8%35%322446%42%
1720
May1st to 15thNight
12%6%25%5%25%45%7%41%
1619
16th to endNight
9%5%245%2335%8%48%
1566
June1st to 15thNight
5%214435%5%6%10%51%
1440
16th to endNight
3212325%46%10%57%
1440
July1st to 15thNight
6%41331446%8%54%
1530
16th to endNight
321343447%10%53%
1702
August1st to 15thNight
331342446%10%55%
1620
16th to endNight
7%324433247%55%
1821
September1st to 15thNight
9%414424446%52%
1818
16th to endNight
8%313423448%54%
1992
October1st to 15thNight
13%5%23312336%53%
2160
16th to endNight
12%5%1432223455%
2304
November1st to 15thNight
9%424323345%56%
2384
16th to endNight
14%6%24322345%50%
2730
December1st to 15thNight
13%8%36%425%445%41%
2730
16th to endNight
15%10%47%423336%37%
2912

Transparency (when cloud cover <= 30%)
Color Meanings:
Too cloudy to forecast Poor Below Average Average Above average Transparent
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
43%5%14%21%14%1
1734
16th to endDay
48%413%21%10%1
1872
February1st to 15thDay
48%5%16%21%7%1
1695
16th to endDay
45%413%20%14%1
1532
March1st to 15thDay
48%5%11%23%9%1
1980
16th to endDay
54%5%11%19%7%1
2112
April1st to 15thDay
45%411%24%12%
2115
16th to endDay
51%5%12%18%10%
2238
May1st to 15thDay
49%7%12%21%9%
2331
16th to endDay
42%6%16%21%12%1
2548
June1st to 15thDay
36%7%12%27%13%1
2520
16th to endDay
28%8%17%29%15%1
2520
July1st to 15thDay
34%7%16%26%11%3
2284
16th to endDay
28%6%15%31%16%1
2311
August1st to 15thDay
33%6%15%26%16%
2326
16th to endDay
34%6%11%24%17%5%
2381
September1st to 15thDay
33%5%10%26%17%4
2139
16th to endDay
31%5%11%31%17%1
1956
October1st to 15thDay
38%39%25%19%3
1800
16th to endDay
34%411%26%18%4
1920
November1st to 15thDay
31%5%13%25%20%3
1803
16th to endDay
38%5%10%28%16%
1560
December1st to 15thDay
46%6%14%21%10%
1560
16th to endDay
49%5%13%20%9%1
1664
January1st to 15thNight
34%5%14%27%16%1
2532
16th to endNight
37%5%15%25%14%1
2704
February1st to 15thNight
49%412%20%11%2
2470
16th to endNight
36%413%23%18%3
1949
March1st to 15thNight
39%412%25%16%2
1980
16th to endNight
49%412%21%8%1
2112
April1st to 15thNight
36%49%28%18%2
1833
16th to endNight
42%5%10%24%14%1
1720
May1st to 15thNight
42%6%11%23%14%1
1620
16th to endNight
34%6%14%26%15%1
1568
June1st to 15thNight
26%7%17%30%15%2
1440
16th to endNight
22%6%15%32%20%3
1440
July1st to 15thNight
25%5%14%33%17%3
1443
16th to endNight
22%6%15%35%18%1
1594
August1st to 15thNight
23%5%17%32%20%1
1610
16th to endNight
29%49%26%22%7%
1821
September1st to 15thNight
31%5%10%25%21%6%
1818
16th to endNight
28%311%33%19%3
1992
October1st to 15thNight
32%39%25%23%5%
2160
16th to endNight
32%38%26%24%4
2304
November1st to 15thNight
29%413%24%21%6%
2384
16th to endNight
36%410%28%18%2
2730
December1st to 15thNight
43%5%12%25%11%
2730
16th to endNight
49%410%21%12%2
2912

Seeing (when cloud cover <= 80%)
Color Meanings:
Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
19%13%39%23%4
135
16th to endDay
15%13%45%20%4
144
February1st to 15thDay
13%21%47%15%2
130
16th to endDay
17%23%33%13%11%1
81
March1st to 15thDay
25%13%45%13%2
90
16th to endDay
29%12%36%19%2
96
April1st to 15thDay
20%9%34%25%9%
234
16th to endDay
25%13%32%18%8%1
348
May1st to 15thDay
17%9%32%28%9%1
468
16th to endDay
17%8%32%24%14%2
517
June1st to 15thDay
9%5%25%35%17%6%
495
16th to endDay
45%32%36%17%4
495
July1st to 15thDay
11%217%36%25%6%
475
16th to endDay
5%11%42%33%6%
515
August1st to 15thDay
7%112%37%33%7%
493
16th to endDay
11%315%35%23%10%
421
September1st to 15thDay
12%115%32%30%7%
294
16th to endDay
10%220%46%11%7%
135
October1st to 15thDay
20%7%30%29%8%4
135
16th to endDay
10%13%34%33%8%
144
November1st to 15thDay
12%5%34%28%10%8%
135
16th to endDay
27%15%33%16%7%
135
December1st to 15thDay
11%25%37%17%5%2
135
16th to endDay
20%18%39%20%
144
January1st to 15thNight
12%13%41%24%6%
975
16th to endNight
12%13%42%27%4
1040
February1st to 15thNight
16%12%39%27%4
950
16th to endNight
14%12%42%24%5%
687
March1st to 15thNight
15%11%36%28%8%
540
16th to endNight
22%11%35%25%5%
576
April1st to 15thNight
13%12%37%29%6%
539
16th to endNight
22%8%33%27%7%1
540
May1st to 15thNight
16%7%32%33%8%1
540
16th to endNight
12%432%35%13%1
563
June1st to 15thNight
6%324%44%19%2
540
16th to endNight
4327%46%17%1
540
July1st to 15thNight
8%114%45%27%2
510
16th to endNight
5%11%45%34%1
564
August1st to 15thNight
3111%50%32%1
539
16th to endNight
8%212%42%28%4
573
September1st to 15thNight
10%216%39%26%4
540
16th to endNight
8%321%38%25%2
549
October1st to 15thNight
16%5%30%30%14%2
720
16th to endNight
15%9%33%30%9%
768
November1st to 15thNight
12%11%33%31%9%
822
16th to endNight
16%11%38%25%7%
975
December1st to 15thNight
18%12%36%25%6%
975
16th to endNight
20%9%38%28%4
1040
Page generated at 2018-02-15 09:58:47. Version ac04

Copyright 2018 A. Danko


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