Carter
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Carter clear sky chart from 2005-11-06 to 2024-01-16.

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%
23876
19%
74588
13%
23822
47%
23822
23%
49080

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 10thNight
18%
760
15%
2459
7%
757
28%
757
13%
1805
January11th to 20thNight
15%
744
14%
2417
6%
744
25%
744
11%
1846
January21st to endNight
18%
792
16%
2574
6%
792
29%
792
14%
1822
February1st to 10thNight
19%
720
13%
2300
5%
720
28%
720
13%
1698
February11th to 20thNight
15%
703
15%
2099
6%
700
24%
700
13%
1535
February21st to endNight
15%
592
16%
1776
6%
592
24%
592
12%
1336
March1st to 10thNight
22%
720
20%
2080
9%
720
32%
720
19%
1403
March11th to 20thNight
22%
720
18%
1980
8%
720
29%
720
19%
1404
March21st to endNight
29%
792
16%
2178
8%
792
35%
792
21%
1523
April1st to 10thNight
30%
702
20%
1962
11%
702
39%
702
26%
1269
April11th to 20thNight
36%
533
24%
1674
13%
533
46%
533
26%
1040
April21st to endNight
30%
540
20%
1620
7%
540
40%
540
23%
1082
May1st to 10thNight
36%
540
16%
1620
9%
540
41%
540
22%
1095
May11th to 20thNight
42%
531
16%
1592
9%
531
47%
531
24%
1065
May21st to endNight
58%
583
19%
1745
14%
582
62%
582
32%
1059
June1st to 10thNight
59%
540
18%
1620
14%
540
63%
540
33%
956
June11th to 20thNight
61%
540
18%
1620
15%
540
63%
540
35%
951
June21st to endNight
60%
540
19%
1620
16%
540
64%
540
36%
967
July1st to 10thNight
62%
525
15%
1575
14%
525
64%
525
30%
994
July11th to 20thNight
70%
522
19%
1566
16%
522
72%
522
37%
909
July21st to endNight
63%
591
20%
1672
17%
558
66%
558
32%
1025
August1st to 10thNight
68%
537
22%
1600
20%
534
69%
534
34%
951
August11th to 20thNight
67%
534
23%
1598
20%
534
69%
534
32%
970
August21st to endNight
66%
594
25%
1875
23%
594
69%
594
37%
1038
September1st to 10thNight
64%
702
24%
1962
18%
702
67%
702
36%
1187
September11th to 20thNight
64%
720
28%
1980
22%
720
68%
720
38%
1175
September21st to endNight
53%
720
27%
1980
19%
720
59%
720
33%
1227
October1st to 10thNight
56%
720
28%
2005
24%
720
62%
720
39%
1159
October11th to 20thNight
41%
720
26%
2160
18%
720
51%
720
29%
1306
October21st to endNight
36%
792
26%
2400
18%
792
47%
792
24%
1571
November1st to 10thNight
45%
740
27%
2406
22%
740
56%
740
29%
1389
November11th to 20thNight
32%
760
24%
2470
15%
760
44%
760
22%
1556
November21st to endNight
33%
760
22%
2470
14%
760
43%
760
21%
1608
December1st to 10thNight
23%
760
14%
2470
7%
760
31%
760
14%
1780
December11th to 20thNight
26%
759
18%
2986
10%
759
37%
759
14%
2050
December21st to endNight
21%
828
10%
4477
7%
817
31%
817
7%
3329

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%8%36%6%35%5%5%7%37%
74921
Night
14%8%36%5%35%5%5%7%39%
74906
TransparencyDay
47%411%23%14%2
74644
Night
45%410%22%15%3
74702
SeeingDay
21%11%26%22%13%6%
13750
Night
19%10%25%28%16%2
23886

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 10thDay
15%11%6%12%6%335%5%6%27%
1706
11th to 20thDay
19%14%5%10%8%34445%23%
1671
21st to endDay
18%14%5%6%6%3445%5%30%
1782
February1st to 10thDay
19%13%5%10%6%24436%27%
1656
11th to 20thDay
20%11%49%5%3445%5%29%
1748
21st to endDay
20%12%48%4335%46%31%
1480
March1st to 10thDay
18%10%36%425%446%37%
1879
11th to 20thDay
20%9%47%7%34446%31%
1980
21st to endDay
20%8%46%6%34446%33%
2178
April1st to 10thDay
13%9%37%5%3445%7%39%
2012
11th to 20thDay
16%8%36%5%3445%6%41%
2235
21st to endDay
17%8%37%6%3445%6%36%
2340
May1st to 10thDay
19%7%36%6%35%5%6%7%34%
2340
11th to 20thDay
18%7%37%7%45%5%46%33%
2301
21st to endDay
9%6%27%7%5%6%7%7%9%37%
2531
June1st to 10thDay
11%6%25%5%36%5%6%9%41%
2340
11th to 20thDay
9%6%26%6%46%6%7%8%41%
2340
21st to endDay
9%5%35%5%46%6%7%10%39%
2340
July1st to 10thDay
13%6%36%6%45%6%6%10%37%
2340
11th to 20thDay
9%5%36%6%47%7%7%9%36%
2340
21st to endDay
13%6%35%6%36%6%6%8%37%
2547
August1st to 10thDay
10%5%35%7%46%6%8%10%37%
2327
11th to 20thDay
10%6%37%6%46%6%6%11%34%
2303
21st to endDay
8%5%26%5%35%6%6%9%45%
2478
September1st to 10thDay
14%6%24425%448%46%
1980
11th to 20thDay
11%6%35%4335%5%8%49%
1980
21st to endDay
16%6%26%434447%45%
1980
October1st to 10thDay
13%4245%345%48%49%
1954
11th to 20thDay
14%6%35%5%3445%6%46%
1800
21st to endDay
19%8%35%5%23346%41%
1954
November1st to 10thDay
11%6%25%424446%51%
1672
11th to 20thDay
14%9%47%6%24446%40%
1710
21st to endDay
16%8%46%5%35%446%40%
1710
December1st to 10thDay
23%13%47%5%245%46%27%
1710
11th to 20thDay
17%13%5%8%6%345%45%31%
2153
21st to endDay
18%16%5%9%7%45%447%21%
3124
January1st to 10thNight
15%12%5%11%7%45%445%28%
2459
11th to 20thNight
21%13%6%9%6%3444425%
2417
21st to endNight
17%10%48%8%35%45%6%31%
2574
February1st to 10thNight
20%12%5%8%5%345%45%28%
2300
11th to 20thNight
20%11%49%6%245%5%5%29%
2098
21st to endNight
22%13%48%6%34345%28%
1776
March1st to 10thNight
18%8%47%434445%39%
2080
11th to 20thNight
18%9%5%6%6%345%5%6%34%
1980
21st to endNight
15%9%36%7%4445%7%35%
2178
April1st to 10thNight
14%7%35%5%35%46%8%40%
1962
11th to 20thNight
14%6%25%5%35%5%5%8%41%
1674
21st to endNight
16%8%26%5%35%45%6%39%
1620
May1st to 10thNight
17%7%46%5%345%5%8%36%
1620
11th to 20thNight
16%6%35%6%36%5%7%8%36%
1592
21st to endNight
8%5%25%5%35%6%7%10%43%
1744
June1st to 10thNight
7%4245%46%5%7%10%45%
1620
11th to 20thNight
6%436%6%35%5%7%11%46%
1620
21st to endNight
7%4235%35%6%8%11%46%
1620
July1st to 10thNight
9%7%245%45%6%6%10%42%
1620
11th to 20thNight
6%425%5%35%6%7%11%47%
1620
21st to endNight
8%6%36%5%446%8%9%43%
1771
August1st to 10thNight
7%5%246%36%5%6%9%47%
1611
11th to 20thNight
8%426%446%5%7%9%44%
1598
21st to endNight
7%425%5%2446%9%50%
1875
September1st to 10thNight
11%424435%45%8%49%
1962
11th to 20thNight
11%5%2443445%7%52%
1980
21st to endNight
11%6%25%43446%7%48%
1980
October1st to 10thNight
10%5%244235%5%8%52%
2005
11th to 20thNight
13%7%25%434447%47%
2160
21st to endNight
18%7%36%434445%42%
2400
November1st to 10thNight
12%7%24434445%51%
2406
11th to 20thNight
14%8%45%5%345%5%6%42%
2470
21st to endNight
17%10%45%5%24446%39%
2470
December1st to 10thNight
19%13%5%8%6%34446%29%
2470
11th to 20thNight
17%10%6%9%6%3445%6%32%
3042
21st to endNight
18%16%5%8%7%45%5%5%6%22%
4532

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 10thDay
58%39%17%11%1
1707
11th to 20thDay
64%39%18%5%1
1671
21st to endDay
56%39%22%8%2
1782
February1st to 10thDay
61%29%18%9%1
1656
11th to 20thDay
58%37%19%11%2
1758
21st to endDay
55%38%21%11%3
1480
March1st to 10thDay
50%38%26%12%2
1879
11th to 20thDay
56%38%19%11%3
1980
21st to endDay
53%39%22%10%2
2178
April1st to 10thDay
46%311%25%13%3
2012
11th to 20thDay
44%39%21%18%4
2235
21st to endDay
48%411%22%11%3
2340
May1st to 10thDay
50%312%23%10%2
2340
11th to 20thDay
52%411%20%11%1
2305
21st to endDay
42%7%15%23%13%1
2531
June1st to 10thDay
39%5%12%26%17%1
2340
11th to 20thDay
39%5%14%23%17%2
2340
21st to endDay
40%6%14%22%15%4
2340
July1st to 10thDay
43%6%15%19%16%1
2275
11th to 20thDay
40%6%13%23%15%2
2271
21st to endDay
41%6%12%26%12%2
2405
August1st to 10thDay
40%6%16%25%13%1
2314
11th to 20thDay
44%412%27%12%1
2303
21st to endDay
35%415%26%16%4
2478
September1st to 10thDay
38%313%22%18%6%
1980
11th to 20thDay
35%410%28%22%1
1980
21st to endDay
41%27%26%22%2
1980
October1st to 10thDay
34%311%26%23%3
1954
11th to 20thDay
40%28%26%21%3
1800
21st to endDay
46%29%24%17%2
1954
November1st to 10thDay
36%38%28%21%4
1672
11th to 20thDay
46%27%22%19%4
1710
21st to endDay
47%29%22%18%1
1710
December1st to 10thDay
58%39%21%8%1
1710
11th to 20thDay
56%39%17%14%1
2150
21st to endDay
65%39%17%6%1
3124
January1st to 10thNight
59%38%18%11%1
2459
11th to 20thNight
63%28%17%8%2
2417
21st to endNight
55%29%23%8%2
2574
February1st to 10thNight
59%39%21%8%1
2300
11th to 20thNight
57%37%21%11%1
2099
21st to endNight
60%210%15%9%3
1776
March1st to 10thNight
48%37%22%17%3
2080
11th to 20thNight
51%49%23%12%2
1980
21st to endNight
49%311%22%13%2
2178
April1st to 10thNight
42%310%25%17%2
1962
11th to 20thNight
41%311%20%18%6%
1674
21st to endNight
46%411%22%14%2
1620
May1st to 10thNight
47%5%12%21%11%3
1620
11th to 20thNight
44%6%14%21%13%2
1593
21st to endNight
35%5%17%23%17%2
1745
June1st to 10thNight
33%6%15%25%17%4
1620
11th to 20thNight
32%6%16%21%21%4
1620
21st to endNight
31%7%15%27%16%4
1620
July1st to 10thNight
37%7%14%22%17%4
1575
11th to 20thNight
30%7%16%25%19%4
1566
21st to endNight
36%6%14%29%14%2
1672
August1st to 10thNight
33%6%15%28%16%2
1600
11th to 20thNight
35%6%14%27%17%1
1598
21st to endNight
30%414%27%19%5%
1875
September1st to 10thNight
34%413%23%18%8%
1962
11th to 20thNight
32%411%24%26%3
1980
21st to endNight
36%49%23%25%2
1980
October1st to 10thNight
32%311%28%22%5%
2005
11th to 20thNight
38%38%25%21%4
2160
21st to endNight
46%27%24%18%4
2400
November1st to 10thNight
37%27%25%24%5%
2406
11th to 20thNight
44%37%20%22%5%
2470
21st to endNight
48%29%25%15%2
2470
December1st to 10thNight
57%310%20%10%1
2470
11th to 20thNight
54%28%23%11%1
3044
21st to endNight
64%28%17%8%
4532

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 10thDay
26%22%34%13%31
270
11th to 20thDay
37%19%33%10%1
257
21st to endDay
33%29%25%10%3
264
February1st to 10thDay
35%22%30%10%2
240
11th to 20thDay
44%23%28%4
240
21st to endDay
38%18%36%7%1
198
March1st to 10thDay
33%20%31%13%3
319
11th to 20thDay
27%20%33%14%5%1
420
21st to endDay
32%16%31%16%5%
462
April1st to 10thDay
23%19%29%20%8%1
420
11th to 20thDay
23%16%33%18%8%3
412
21st to endDay
26%16%33%18%5%2
420
May1st to 10thDay
26%15%31%16%10%2
423
11th to 20thDay
21%10%31%23%10%5%
447
21st to endDay
15%8%24%28%16%10%
485
June1st to 10thDay
12%6%24%32%18%8%
450
11th to 20thDay
12%8%26%29%16%9%
450
21st to endDay
12%6%28%28%16%11%
450
July1st to 10thDay
17%313%25%17%24%
445
11th to 20thDay
8%5%22%33%19%13%
444
21st to endDay
15%218%30%23%12%
488
August1st to 10thDay
12%318%30%24%13%
446
11th to 20thDay
16%315%32%23%10%
439
21st to endDay
10%317%29%26%14%
495
September1st to 10thDay
17%314%27%27%12%
450
11th to 20thDay
14%213%29%30%13%
450
21st to endDay
20%7%20%26%22%5%
450
October1st to 10thDay
15%6%24%28%19%8%
450
11th to 20thDay
16%15%31%21%14%3
450
21st to endDay
24%12%31%22%10%
469
November1st to 10thDay
19%12%35%24%9%1
270
11th to 20thDay
27%17%29%20%6%2
270
21st to endDay
26%14%37%17%41
270
December1st to 10thDay
33%17%30%13%6%
270
11th to 20thDay
27%19%33%15%5%1
270
21st to endDay
34%18%33%12%21
297
January1st to 10thNight
26%18%31%19%5%
760
11th to 20thNight
32%16%31%18%3
744
21st to endNight
24%20%34%20%3
792
February1st to 10thNight
30%15%32%21%2
720
11th to 20thNight
31%19%30%19%1
703
21st to endNight
33%18%30%19%1
592
March1st to 10thNight
25%16%31%23%5%
720
11th to 20thNight
25%17%31%19%8%
720
21st to endNight
21%14%32%27%7%
792
April1st to 10thNight
22%12%32%25%9%
702
11th to 20thNight
19%10%29%29%11%1
533
21st to endNight
19%9%36%28%8%1
540
May1st to 10thNight
20%10%28%27%12%3
540
11th to 20thNight
18%5%24%34%16%2
531
21st to endNight
10%417%34%28%6%
584
June1st to 10thNight
9%322%41%23%3
540
11th to 20thNight
6%320%38%27%5%
540
21st to endNight
9%321%38%26%4
540
July1st to 10thNight
13%312%30%31%11%
525
11th to 20thNight
6%213%37%37%5%
522
21st to endNight
10%312%36%33%6%
591
August1st to 10thNight
9%29%38%35%7%
537
11th to 20thNight
10%39%36%36%7%
534
21st to endNight
9%212%35%34%9%
594
September1st to 10thNight
13%212%31%35%7%
702
11th to 20thNight
13%213%32%34%7%
720
21st to endNight
14%6%20%30%28%2
720
October1st to 10thNight
13%5%19%33%26%4
720
11th to 20thNight
17%8%29%28%16%2
720
21st to endNight
22%9%28%25%13%2
792
November1st to 10thNight
15%12%23%32%16%2
740
11th to 20thNight
20%14%28%27%9%1
760
21st to endNight
24%13%25%27%9%1
760
December1st to 10thNight
29%16%27%24%4
760
11th to 20thNight
23%14%31%25%6%1
760
21st to endNight
30%14%29%24%3
836
Page generated at 2024-01-13 18:28:34. Version ac07

Copyright 2024 Attilla Danko


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