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 2017-12-04.

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%
15823
20%
47875
13%
15779
47%
15779
24%
31213

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
25%
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
14%
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
31%
647
20%
1896
11%
647
41%
647
25%
1205
April16th to endNight
35%
540
22%
1620
10%
540
45%
540
24%
1049
May1st to 15thNight
36%
540
15%
1620
8%
540
42%
540
21%
1104
May16th to endNight
54%
562
19%
1684
14%
561
58%
561
30%
1040
June1st to 15thNight
60%
540
18%
1620
15%
540
64%
540
36%
932
June16th to endNight
62%
540
18%
1620
14%
540
65%
540
38%
937
July1st to 15thNight
57%
510
14%
1530
13%
510
59%
510
30%
960
July16th to endNight
69%
564
19%
1595
16%
531
71%
531
36%
929
August1st to 15thNight
69%
539
23%
1609
19%
536
72%
536
36%
936
August16th to endNight
69%
573
25%
1782
23%
573
71%
573
37%
992
September1st to 15thNight
62%
708
25%
1968
20%
708
64%
708
35%
1206
September16th to endNight
59%
717
28%
1980
23%
717
62%
717
34%
1208
October1st to 15thNight
54%
720
30%
2058
25%
720
60%
720
37%
1185
October16th to endNight
38%
768
27%
2321
19%
768
49%
768
27%
1468
November1st to 15thNight
42%
760
26%
2471
21%
760
52%
760
27%
1466
November16th to endNight
32%
780
24%
2535
15%
780
43%
780
22%
1614
December1st to 15thNight
25%
736
13%
2391
8%
736
32%
736
15%
1719
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
14%7%36%5%3445%7%36%
48608
Night
13%7%35%5%2445%7%39%
48068
Cloud CoverDay
15%7%36%5%3445%7%36%
48618
Night
13%7%35%5%2445%7%39%
48072
TransparencyDay
46%411%22%13%2
48319
Night
44%310%22%15%2
47875
SeeingDay
18%9%23%22%16%9%
5641
Night
18%10%24%27%16%2
15824

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
15%7%45%423346%40%
2061
16th to endDay
15%7%245%3445%6%39%
2340
May1st to 15thDay
21%7%36%5%3435%7%30%
2331
16th to endDay
10%5%36%6%46%6%5%8%36%
2431
June1st to 15thDay
9%5%26%5%36%5%6%8%41%
2340
16th to endDay
8%5%25%6%37%6%6%9%37%
2340
July1st to 15thDay
14%5%27%7%25%5%7%9%32%
2340
16th to endDay
10%5%36%5%46%7%8%8%32%
2465
August1st to 15thDay
8%6%26%7%46%6%7%10%34%
2340
16th to endDay
8%5%25%6%345%6%9%40%
2418
September1st to 15thDay
12%5%35%4235%5%8%42%
1980
16th to endDay
15%5%245%23345%46%
1980
October1st to 15thDay
13%5%24423447%47%
1902
16th to endDay
20%6%25%312236%45%
1902
November1st to 15thDay
12%7%35%5%24346%45%
1717
16th to endDay
15%8%35%5%24345%40%
1755
December1st to 15thDay
23%11%45%433445%28%
1651
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%6%3442445%8%40%
1896
16th to endNight
13%7%35%5%245%46%41%
1620
May1st to 15thNight
17%7%35%5%345%5%9%33%
1620
16th to endNight
10%5%24425%5%6%8%42%
1682
June1st to 15thNight
6%3236%25%5%6%10%46%
1620
16th to endNight
6%3235%245%7%12%46%
1620
July1st to 15thNight
9%6%345%35%46%8%42%
1620
16th to endNight
6%4145%35%6%7%11%44%
1703
August1st to 15thNight
6%2245%35%5%6%8%49%
1620
16th to endNight
6%3244245%6%10%49%
1782
September1st to 15thNight
12%423424447%48%
1968
16th to endNight
10%6%2432445%7%49%
1980
October1st to 15thNight
10%424423448%51%
2058
16th to endNight
15%6%25%434335%44%
2321
November1st to 15thNight
14%6%24423345%48%
2471
16th to endNight
17%8%25%423346%40%
2535
December1st to 15thNight
19%11%47%5%24346%29%
2391
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%7%35%433346%40%
2061
16th to endDay
15%7%26%5%24446%40%
2340
May1st to 15thDay
21%7%26%5%35%447%30%
2331
16th to endDay
10%5%26%7%45%6%5%7%36%
2431
June1st to 15thDay
9%5%25%6%36%5%6%8%40%
2340
16th to endDay
9%425%5%46%6%6%9%37%
2340
July1st to 15thDay
14%5%26%6%35%5%6%9%33%
2340
16th to endDay
11%5%35%6%37%7%7%8%33%
2465
August1st to 15thDay
9%5%35%7%46%6%6%10%34%
2340
16th to endDay
8%5%26%5%346%6%9%41%
2418
September1st to 15thDay
13%5%35%32445%8%42%
1980
16th to endDay
15%6%24423446%46%
1980
October1st to 15thDay
12%424433447%47%
1902
16th to endDay
19%6%24322235%45%
1902
November1st to 15thDay
12%7%35%423446%45%
1717
16th to endDay
15%8%35%5%25%335%40%
1755
December1st to 15thDay
23%11%36%423445%28%
1651
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%34435%35%7%41%
1896
16th to endNight
14%6%25%5%25%45%7%40%
1620
May1st to 15thNight
17%7%36%42445%9%34%
1619
16th to endNight
10%4245%25%5%7%9%42%
1682
June1st to 15thNight
6%2235%35%5%6%10%46%
1620
16th to endNight
6%3234345%7%11%47%
1620
July1st to 15thNight
9%6%345%245%6%8%42%
1620
16th to endNight
6%4245%346%8%10%44%
1703
August1st to 15thNight
6%3235%35%5%6%9%48%
1620
16th to endNight
6%32442446%9%50%
1782
September1st to 15thNight
11%424424448%48%
1968
16th to endNight
10%6%2442445%6%49%
1980
October1st to 15thNight
10%5%14422448%51%
2058
16th to endNight
16%6%35%424335%44%
2321
November1st to 15thNight
14%6%23424345%48%
2471
16th to endNight
17%8%35%413345%41%
2535
December1st to 15thNight
20%11%47%5%24346%28%
2391
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%29%23%14%3
2061
16th to endDay
44%410%21%14%5%
2340
May1st to 15thDay
53%312%18%9%1
2331
16th to endDay
43%6%13%22%12%1
2435
June1st to 15thDay
39%5%13%24%16%1
2340
16th to endDay
41%6%13%19%17%2
2340
July1st to 15thDay
46%5%12%17%14%2
2201
16th to endDay
42%7%13%23%12%1
2310
August1st to 15thDay
42%6%13%22%13%1
2327
16th to endDay
37%413%26%14%3
2418
September1st to 15thDay
39%312%21%18%4
1980
16th to endDay
40%26%24%23%1
1980
October1st to 15thDay
36%39%26%21%3
1902
16th to endDay
42%19%27%16%1
1902
November1st to 15thDay
40%37%25%18%4
1717
16th to endDay
45%28%23%18%1
1755
December1st to 15thDay
57%39%19%8%1
1651
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
1896
16th to endNight
42%49%21%15%5%
1620
May1st to 15thNight
46%5%13%20%10%2
1620
16th to endNight
36%6%15%22%16%2
1684
June1st to 15thNight
30%6%16%25%18%3
1620
16th to endNight
28%7%17%24%19%3
1620
July1st to 15thNight
38%5%12%22%16%4
1530
16th to endNight
30%6%17%27%15%2
1595
August1st to 15thNight
30%6%15%24%19%2
1609
16th to endNight
29%5%13%26%20%4
1782
September1st to 15thNight
35%411%20%20%7%
1968
16th to endNight
34%48%22%28%1
1980
October1st to 15thNight
32%210%28%20%5%
2058
16th to endNight
42%17%25%19%2
2321
November1st to 15thNight
38%26%22%22%6%
2471
16th to endNight
45%27%25%16%1
2535
December1st to 15thNight
56%39%19%9%1
2391
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%15%28%22%10%1
270
16th to endDay
17%12%34%19%10%6%
270
May1st to 15thDay
28%10%29%15%10%5%
288
16th to endDay
15%7%29%22%13%12%
331
June1st to 15thDay
9%6%19%36%17%11%
315
16th to endDay
11%8%25%26%16%12%
315
July1st to 15thDay
20%5%18%27%9%17%
305
16th to endDay
9%213%26%25%21%
326
August1st to 15thDay
11%311%28%27%17%
313
16th to endDay
11%213%28%27%16%
332
September1st to 15thDay
16%312%24%27%15%
315
16th to endDay
17%214%21%31%12%
314
October1st to 15thDay
14%6%22%26%20%8%
315
16th to endDay
17%12%28%21%17%2
318
November1st to 15thDay
24%11%26%22%11%3
135
16th to endDay
21%17%32%20%7%1
135
December1st to 15thDay
26%22%24%16%11%1
100
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
20%11%32%23%10%
647
16th to endNight
16%8%33%28%11%1
540
May1st to 15thNight
20%9%27%27%13%2
540
16th to endNight
11%5%19%32%25%5%
563
June1st to 15thNight
6%221%39%26%4
540
16th to endNight
7%220%38%27%3
540
July1st to 15thNight
13%314%34%29%4
510
16th to endNight
6%211%32%37%7%
564
August1st to 15thNight
6%110%36%37%6%
539
16th to endNight
6%210%34%36%8%
573
September1st to 15thNight
14%212%29%33%7%
708
16th to endNight
13%415%25%35%5%
717
October1st to 15thNight
13%6%20%30%24%4
720
16th to endNight
19%9%28%22%17%1
768
November1st to 15thNight
17%10%23%27%17%2
760
16th to endNight
23%14%25%24%10%1
780
December1st to 15thNight
28%14%24%24%6%
736
16th to endNight
27%15%32%20%3
768
Page generated at 2017-12-05 09:18:59. Version ac04

Copyright 2017 A. Danko


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