Carter
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Carter clear sky chart from 2005-11-05 to 2017-04-01.

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
39%
14986
20%
45363
13%
14942
46%
14942
23%
29727

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
15%
720
14%
2327
7%
716
24%
716
11%
1756
January16th to endNight
18%
768
16%
2496
7%
768
29%
768
13%
1785
February1st to 15thNight
18%
704
14%
2205
5%
701
28%
701
15%
1579
February16th to endNight
16%
631
15%
1893
6%
631
24%
631
14%
1392
March1st to 15thNight
24%
720
19%
2046
10%
720
31%
720
18%
1431
March16th to endNight
28%
768
16%
2112
9%
768
34%
768
21%
1469
April1st to 15thNight
30%
597
22%
1749
11%
597
40%
597
25%
1117
April16th to endNight
35%
495
22%
1485
10%
495
45%
495
25%
960
May1st to 15thNight
37%
495
16%
1485
9%
495
43%
495
22%
1004
May16th to endNight
55%
514
18%
1540
14%
513
59%
513
30%
949
June1st to 15thNight
60%
495
19%
1485
15%
495
63%
495
35%
864
June16th to endNight
63%
495
16%
1485
13%
495
66%
495
38%
855
July1st to 15thNight
58%
465
15%
1395
14%
465
60%
465
29%
881
July16th to endNight
68%
522
17%
1469
13%
489
70%
489
36%
863
August1st to 15thNight
70%
494
25%
1474
21%
491
73%
491
37%
848
August16th to endNight
69%
525
23%
1633
22%
525
70%
525
37%
913
September1st to 15thNight
63%
649
27%
1804
21%
649
66%
649
36%
1100
September16th to endNight
57%
657
26%
1815
21%
657
60%
657
32%
1130
October1st to 15thNight
53%
660
31%
1886
26%
660
59%
660
37%
1087
October16th to endNight
37%
704
25%
2127
17%
704
48%
704
26%
1356
November1st to 15thNight
44%
700
27%
2276
22%
700
54%
700
29%
1324
November16th to endNight
31%
720
22%
2340
14%
720
41%
720
20%
1516
December1st to 15thNight
24%
720
14%
2340
8%
720
31%
720
14%
1697
December16th to endNight
20%
768
15%
2496
6%
768
31%
768
13%
1851

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
15%7%36%5%3445%7%35%
45731
Night
14%7%35%5%2445%7%39%
45556
Cloud CoverDay
15%7%36%5%3445%7%36%
45741
Night
14%7%35%5%2445%7%39%
45560
TransparencyDay
47%411%22%13%2
45442
Night
44%310%22%15%2
45363
SeeingDay
19%9%22%21%16%9%
4697
Night
18%10%24%26%16%2
14987

By Month

Percentage Cloud Cover NE (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
17%12%7%10%5%33435%25%
1611
16th to endDay
17%12%5%7%5%24446%29%
1728
February1st to 15thDay
17%12%5%9%6%23435%29%
1654
16th to endDay
15%13%47%4345%46%29%
1580
March1st to 15thDay
22%9%36%5%25%335%32%
1902
16th to endDay
18%8%36%6%34445%33%
2112
April1st to 15thDay
16%7%45%423346%40%
1893
16th to endDay
16%7%345%34446%40%
2145
May1st to 15thDay
21%7%26%6%45%45%7%29%
2136
16th to endDay
9%5%37%7%46%5%5%8%36%
2223
June1st to 15thDay
9%5%26%5%36%5%6%8%40%
2145
16th to endDay
8%5%26%6%47%6%6%9%36%
2145
July1st to 15thDay
14%5%36%7%35%5%7%9%31%
2145
16th to endDay
10%6%36%5%46%7%8%9%30%
2283
August1st to 15thDay
7%5%26%7%46%6%7%10%34%
2145
16th to endDay
8%6%25%5%345%6%9%40%
2216
September1st to 15thDay
11%5%35%4235%5%8%42%
1815
16th to endDay
16%6%245%23345%44%
1815
October1st to 15thDay
12%5%24423447%48%
1744
16th to endDay
20%6%25%312336%44%
1744
November1st to 15thDay
11%6%35%424336%47%
1582
16th to endDay
16%8%36%5%24445%39%
1620
December1st to 15thDay
23%11%45%434446%27%
1620
16th to endDay
20%13%5%7%423336%28%
1728
January1st to 15thNight
18%11%5%11%7%3443425%
2327
16th to endNight
16%10%48%6%35%44430%
2496
February1st to 15thNight
17%11%47%5%2344431%
2203
16th to endNight
16%12%5%7%6%35%45%6%27%
1893
March1st to 15thNight
17%7%46%5%3445%6%33%
2034
16th to endNight
14%8%36%6%3445%6%35%
2112
April1st to 15thNight
14%7%3442446%7%40%
1749
16th to endNight
14%6%35%5%245%46%41%
1485
May1st to 15thNight
17%7%35%4235%6%9%33%
1485
16th to endNight
10%5%24425%5%6%8%43%
1538
June1st to 15thNight
6%3236%25%5%6%11%45%
1485
16th to endNight
6%3234245%6%12%46%
1485
July1st to 15thNight
9%6%34435%46%8%42%
1485
16th to endNight
6%4145%35%6%7%11%43%
1577
August1st to 15thNight
5%2245%35%5%6%8%50%
1485
16th to endNight
6%3244345%5%10%49%
1633
September1st to 15thNight
11%42342445%7%49%
1804
16th to endNight
11%6%24424447%47%
1815
October1st to 15thNight
10%5%24413348%51%
1886
16th to endNight
16%7%25%434335%43%
2127
November1st to 15thNight
14%6%24323345%50%
2276
16th to endNight
18%8%35%423346%39%
2340
December1st to 15thNight
20%11%47%5%24345%28%
2340
16th to endNight
20%11%5%6%5%34445%26%
2496

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
18%12%6%11%5%23435%25%
1611
16th to endDay
18%12%5%6%6%33446%29%
1728
February1st to 15thDay
17%12%5%10%5%23435%29%
1654
16th to endDay
15%13%48%4345%45%29%
1580
March1st to 15thDay
22%9%36%5%25%335%32%
1913
16th to endDay
19%7%46%6%33446%33%
2111
April1st to 15thDay
16%8%35%5%34346%40%
1893
16th to endDay
15%7%25%5%24445%41%
2145
May1st to 15thDay
21%7%26%5%35%5%47%29%
2136
16th to endDay
10%5%26%7%46%6%5%7%36%
2223
June1st to 15thDay
9%5%25%6%36%5%6%8%39%
2145
16th to endDay
9%425%6%46%6%6%9%36%
2145
July1st to 15thDay
15%5%26%6%35%5%6%9%32%
2145
16th to endDay
11%6%35%6%37%7%7%9%31%
2283
August1st to 15thDay
8%5%35%7%46%6%6%10%34%
2145
16th to endDay
8%6%26%5%346%5%9%40%
2216
September1st to 15thDay
12%5%35%32446%8%43%
1815
16th to endDay
16%6%24423445%44%
1815
October1st to 15thDay
12%5%24433347%47%
1744
16th to endDay
20%6%24312236%44%
1744
November1st to 15thDay
11%7%35%423436%47%
1582
16th to endDay
16%8%45%5%25%335%39%
1620
December1st to 15thDay
24%11%36%423445%28%
1620
16th to endDay
20%13%47%423336%28%
1728
January1st to 15thNight
18%11%5%11%6%34435%25%
2327
16th to endNight
17%10%5%8%6%35%445%30%
2496
February1st to 15thNight
17%12%47%5%2444431%
2196
16th to endNight
17%12%48%6%3445%6%27%
1893
March1st to 15thNight
17%7%47%5%445%5%5%34%
2046
16th to endNight
15%8%35%6%44446%35%
2112
April1st to 15thNight
14%6%3443446%7%41%
1749
16th to endNight
14%6%25%5%25%45%6%41%
1485
May1st to 15thNight
16%7%36%42445%9%34%
1484
16th to endNight
11%4245%25%5%6%9%43%
1538
June1st to 15thNight
6%2236%35%5%6%11%45%
1485
16th to endNight
6%3234245%6%12%47%
1485
July1st to 15thNight
10%6%345%245%6%8%42%
1485
16th to endNight
6%4245%346%8%11%43%
1577
August1st to 15thNight
6%3235%25%5%6%9%49%
1485
16th to endNight
6%32442446%9%50%
1633
September1st to 15thNight
11%424424448%49%
1804
16th to endNight
11%6%24424446%47%
1815
October1st to 15thNight
10%5%14423448%51%
1886
16th to endNight
16%6%35%424335%43%
2127
November1st to 15thNight
14%5%23324345%50%
2276
16th to endNight
18%8%35%423345%39%
2340
December1st to 15thNight
20%11%47%5%24346%28%
2340
16th to endNight
20%12%5%7%5%34445%27%
2496

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
61%38%17%8%
1612
16th to endDay
56%210%22%6%1
1728
February1st to 15thDay
58%29%19%9%1
1656
16th to endDay
55%310%22%8%
1580
March1st to 15thDay
55%39%21%8%1
1913
16th to endDay
52%39%23%9%1
2112
April1st to 15thDay
45%210%23%14%3
1893
16th to endDay
44%39%21%15%5%
2145
May1st to 15thDay
54%412%18%8%1
2136
16th to endDay
43%5%14%21%12%1
2227
June1st to 15thDay
39%5%14%24%14%
2145
16th to endDay
42%6%13%19%16%2
2145
July1st to 15thDay
47%5%12%17%14%2
2006
16th to endDay
43%7%13%23%10%1
2128
August1st to 15thDay
41%6%13%23%13%1
2132
16th to endDay
38%412%26%14%3
2216
September1st to 15thDay
37%312%21%19%4
1815
16th to endDay
42%26%23%23%1
1815
October1st to 15thDay
36%39%27%20%3
1744
16th to endDay
43%29%27%16%1
1744
November1st to 15thDay
39%36%25%20%4
1582
16th to endDay
47%29%21%18%1
1620
December1st to 15thDay
57%39%19%8%1
1620
16th to endDay
58%312%17%7%
1728
January1st to 15thNight
61%27%14%10%1
2327
16th to endNight
56%29%21%8%1
2496
February1st to 15thNight
55%29%21%9%1
2205
16th to endNight
56%310%20%8%
1893
March1st to 15thNight
50%39%22%11%1
2046
16th to endNight
48%411%23%11%
2112
April1st to 15thNight
41%39%22%19%3
1749
16th to endNight
42%49%20%16%6%
1485
May1st to 15thNight
45%6%14%20%10%2
1485
16th to endNight
36%5%15%22%17%2
1540
June1st to 15thNight
31%6%16%25%17%3
1485
16th to endNight
28%7%18%24%18%3
1485
July1st to 15thNight
38%6%12%21%17%4
1395
16th to endNight
31%6%18%26%14%2
1469
August1st to 15thNight
29%6%15%25%21%2
1474
16th to endNight
29%5%12%26%20%4
1633
September1st to 15thNight
34%412%19%21%7%
1804
16th to endNight
36%47%20%28%1
1815
October1st to 15thNight
32%39%30%19%5%
1886
16th to endNight
43%18%25%18%2
2127
November1st to 15thNight
37%26%22%24%6%
2276
16th to endNight
47%28%24%15%1
2340
December1st to 15thNight
57%310%18%9%1
2340
16th to endNight
59%210%17%8%
2496

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
33%23%31%7%13
90
16th to endDay
40%28%19%9%2
96
February1st to 15thDay
30%32%28%6%2
90
16th to endDay
34%11%41%11%1
81
March1st to 15thDay
33%14%31%15%5%
203
16th to endDay
22%15%35%16%8%1
288
April1st to 15thDay
22%16%27%22%10%
212
16th to endDay
16%12%30%19%13%7%
210
May1st to 15thDay
26%7%30%17%11%7%
228
16th to endDay
14%5%25%24%14%14%
267
June1st to 15thDay
9%6%20%36%16%11%
255
16th to endDay
11%5%24%25%17%14%
255
July1st to 15thDay
22%6%17%22%10%19%
245
16th to endDay
10%211%27%23%24%
270
August1st to 15thDay
9%111%28%28%20%
253
16th to endDay
12%210%25%28%19%
268
September1st to 15thDay
13%27%25%32%17%
255
16th to endDay
21%214%20%30%9%
254
October1st to 15thDay
14%6%23%25%20%9%
255
16th to endDay
17%14%27%22%17%
256
November1st to 15thDay
21%11%25%21%15%5%
90
16th to endDay
25%18%32%16%5%1
90
December1st to 15thDay
26%24%26%16%41
90
16th to endDay
36%23%32%6%1
96
January1st to 15thNight
28%18%31%17%4
720
16th to endNight
24%19%33%20%1
768
February1st to 15thNight
28%16%32%22%
704
16th to endNight
26%20%31%19%1
631
March1st to 15thNight
24%15%29%24%5%
720
16th to endNight
19%13%32%25%9%
768
April1st to 15thNight
21%12%32%23%9%
597
16th to endNight
16%9%32%28%11%1
495
May1st to 15thNight
19%8%26%28%14%2
495
16th to endNight
12%418%32%26%6%
515
June1st to 15thNight
6%222%41%24%3
495
16th to endNight
7%220%37%28%3
495
July1st to 15thNight
13%314%33%29%4
465
16th to endNight
6%211%32%37%8%
522
August1st to 15thNight
6%110%37%37%6%
494
16th to endNight
7%211%33%36%8%
525
September1st to 15thNight
13%211%29%34%7%
649
16th to endNight
14%5%15%27%33%3
657
October1st to 15thNight
13%6%21%30%23%4
660
16th to endNight
20%9%28%23%16%1
704
November1st to 15thNight
17%10%22%27%18%2
700
16th to endNight
24%15%24%24%9%1
720
December1st to 15thNight
29%14%24%24%6%
720
16th to endNight
27%15%32%20%3
768
Page generated at 2017-04-02 06:39:08. Version ac04

Copyright 2017 A. Danko


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