Carpenter Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Carpenter Observatory clear sky chart from 2005-11-06 to 2024-02-15.

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
33%
23332
19%
80167
10%
23236
44%
23236
20%
50973

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
17%
753
20%
4350
7%
737
36%
737
11%
2503
January11th to 20thNight
22%
760
21%
4211
6%
740
37%
740
10%
2511
January21st to endNight
18%
831
13%
4479
6%
814
36%
814
11%
2932
February1st to 10thNight
20%
760
18%
2470
8%
760
34%
760
17%
1614
February11th to 20thNight
11%
722
18%
2241
3%
719
30%
719
15%
1501
February21st to endNight
15%
592
23%
1776
6%
592
34%
592
16%
1185
March1st to 10thNight
22%
720
22%
2115
8%
720
39%
720
22%
1324
March11th to 20thNight
20%
720
21%
1980
8%
720
33%
720
21%
1336
March21st to endNight
21%
792
21%
2082
7%
792
32%
792
24%
1405
April1st to 10thNight
20%
720
18%
1800
3%
720
29%
720
21%
1241
April11th to 20thNight
27%
711
18%
1775
6%
711
33%
711
27%
1191
April21st to endNight
28%
720
19%
1800
4%
720
36%
720
25%
1231
May1st to 10thNight
32%
564
15%
1644
7%
564
38%
564
19%
1142
May11th to 20thNight
35%
354
17%
1416
11%
354
44%
354
15%
921
May21st to endNight
45%
388
15%
1551
14%
388
51%
388
18%
981
June1st to 10thNight
45%
360
18%
1440
17%
360
55%
360
21%
880
June11th to 20thNight
48%
360
14%
1440
15%
360
56%
360
21%
878
June21st to endNight
56%
360
16%
1440
19%
360
61%
360
25%
836
July1st to 10thNight
53%
350
13%
1400
16%
350
56%
350
19%
899
July11th to 20thNight
59%
348
17%
1392
18%
348
62%
348
25%
778
July21st to endNight
59%
474
16%
1562
14%
448
63%
448
25%
972
August1st to 10thNight
63%
537
16%
1600
12%
534
65%
534
29%
1021
August11th to 20thNight
55%
645
16%
1709
10%
645
56%
645
26%
1172
August21st to endNight
55%
792
17%
1980
8%
792
57%
792
32%
1329
September1st to 10thNight
49%
720
22%
1800
9%
720
55%
720
32%
1202
September11th to 20thNight
58%
720
29%
1800
19%
720
61%
720
37%
1131
September21st to endNight
48%
720
23%
2023
16%
720
54%
720
27%
1336
October1st to 10thNight
41%
720
17%
2160
12%
720
48%
720
24%
1409
October11th to 20thNight
39%
720
22%
2160
15%
720
49%
720
28%
1329
October21st to endNight
31%
792
24%
2404
13%
792
45%
792
25%
1511
November1st to 10thNight
36%
740
24%
2407
14%
740
52%
740
28%
1378
November11th to 20thNight
30%
760
24%
2470
13%
760
44%
760
22%
1524
November21st to endNight
28%
760
21%
2648
10%
760
44%
760
21%
1573
December1st to 10thNight
21%
760
17%
2660
6%
760
35%
760
15%
1774
December11th to 20thNight
24%
760
18%
3195
7%
759
39%
759
14%
2000
December21st to endNight
23%
827
12%
4787
8%
817
37%
817
10%
3023

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%6%35%5%35%5%6%8%39%
78307
Night
16%6%35%5%3445%7%41%
80762
TransparencyDay
42%7%13%22%14%2
78017
Night
41%7%13%22%15%2
80586
SeeingDay
20%15%28%22%11%3
13883
Night
19%13%30%27%10%1
23354

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 10thDay
15%6%345%4446%6%42%
2517
11th to 20thDay
14%11%5%8%6%45%5%5%7%32%
2648
21st to endDay
20%10%48%6%34445%33%
3124
February1st to 10thDay
15%7%36%6%35%5%6%7%36%
1710
11th to 20thDay
15%7%47%5%35%45%8%38%
1702
21st to endDay
19%9%46%5%34445%36%
1480
March1st to 10thDay
13%6%25%5%35%5%5%7%45%
1840
11th to 20thDay
16%7%35%6%45%46%8%37%
1980
21st to endDay
20%7%35%5%345%46%38%
2273
April1st to 10thDay
15%7%36%5%345%5%8%39%
2160
11th to 20thDay
16%5%36%5%3346%7%42%
2134
21st to endDay
17%5%25%5%445%6%8%38%
2160
May1st to 10thDay
17%6%25%6%35%5%6%8%36%
2330
11th to 20thDay
21%7%35%5%35%46%8%35%
2478
21st to endDay
14%6%25%5%45%5%7%7%40%
2725
June1st to 10thDay
13%6%25%6%346%7%10%38%
2520
11th to 20thDay
14%6%25%6%45%7%7%9%37%
2520
21st to endDay
12%425%5%45%6%7%10%41%
2520
July1st to 10thDay
10%6%26%6%46%6%7%10%37%
2520
11th to 20thDay
8%325%6%36%8%8%9%42%
2520
21st to endDay
9%6%36%7%47%6%7%9%37%
2660
August1st to 10thDay
11%5%36%6%46%7%8%8%37%
2327
11th to 20thDay
12%5%36%6%35%5%6%9%40%
2174
21st to endDay
14%5%345%45%5%7%9%40%
2376
September1st to 10thDay
17%5%25%4345%5%7%43%
2160
11th to 20thDay
13%5%2442445%8%49%
2160
21st to endDay
18%5%37%5%34446%40%
1931
October1st to 10thDay
19%6%2432446%8%42%
1800
11th to 20thDay
17%6%26%5%33448%44%
1800
21st to endDay
21%6%2443345%7%41%
1949
November1st to 10thDay
13%7%24323447%50%
1671
11th to 20thDay
17%5%2442445%8%44%
1710
21st to endDay
16%5%34436%5%6%7%42%
1530
December1st to 10thDay
18%8%36%5%345%6%7%35%
1520
11th to 20thDay
21%6%25%43436%7%39%
1906
21st to endDay
18%8%36%7%45%5%6%7%31%
2772
January1st to 10thNight
16%6%36%6%34447%40%
4429
11th to 20thNight
17%8%35%435%45%7%39%
4308
21st to endNight
23%9%36%5%33345%36%
4532
February1st to 10thNight
17%8%345%35%45%7%39%
2470
11th to 20thNight
17%7%36%5%345%5%5%38%
2239
21st to endNight
19%7%35%5%3445%6%40%
1776
March1st to 10thNight
14%5%35%5%3445%7%45%
2105
11th to 20thNight
18%7%25%5%35%445%43%
1979
21st to endNight
17%7%345%3445%7%42%
2082
April1st to 10thNight
17%7%35%5%45%45%8%39%
1800
11th to 20thNight
14%6%25%6%3446%7%43%
1775
21st to endNight
20%42442445%6%43%
1800
May1st to 10thNight
19%8%26%5%34448%37%
1644
11th to 20thNight
18%5%46%4346%5%6%38%
1415
21st to endNight
15%6%36%5%2446%8%41%
1550
June1st to 10thNight
16%5%35%5%3446%9%42%
1440
11th to 20thNight
12%5%25%447%5%6%9%40%
1440
21st to endNight
12%415%5%445%7%11%44%
1440
July1st to 10thNight
9%5%37%7%46%6%6%9%39%
1440
11th to 20thNight
7%5%247%35%5%7%10%45%
1440
21st to endNight
10%5%25%5%46%6%6%10%41%
1654
August1st to 10thNight
9%6%36%5%445%7%8%43%
1611
11th to 20thNight
12%5%37%7%45%5%6%7%40%
1709
21st to endNight
13%5%246%25%6%6%8%43%
1980
September1st to 10thNight
15%5%25%43345%7%46%
1800
11th to 20thNight
13%42343435%7%52%
1800
21st to endNight
18%5%245%35%45%6%43%
2023
October1st to 10thNight
20%6%24423437%44%
2160
11th to 20thNight
17%5%25%43435%7%47%
2160
21st to endNight
19%6%24423446%46%
2404
November1st to 10thNight
12%5%244345%47%51%
2407
11th to 20thNight
16%6%35%42335%6%46%
2470
21st to endNight
15%5%25%5%3445%8%44%
2648
December1st to 10thNight
20%7%26%5%35%45%6%36%
2660
11th to 20thNight
18%6%36%43445%6%40%
3288
21st to endNight
18%8%36%6%35%5%5%7%35%
4884

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
41%6%15%25%11%2
2518
11th to 20thDay
51%7%12%17%12%2
2648
21st to endDay
52%8%12%20%8%1
3124
February1st to 10thDay
46%7%13%21%11%1
1710
11th to 20thDay
46%6%11%24%11%2
1711
21st to endDay
51%5%9%21%10%3
1480
March1st to 10thDay
40%5%13%27%13%2
1843
11th to 20thDay
45%6%12%19%14%4
1980
21st to endDay
48%5%10%18%16%3
2273
April1st to 10thDay
43%6%11%21%14%5%
2160
11th to 20thDay
40%7%12%21%16%4
2134
21st to endDay
42%7%11%20%15%5%
2160
May1st to 10thDay
45%9%10%18%14%3
2330
11th to 20thDay
47%8%12%19%13%2
2482
21st to endDay
41%10%13%21%13%2
2725
June1st to 10thDay
40%9%14%22%13%1
2520
11th to 20thDay
42%9%15%22%10%3
2520
21st to endDay
36%10%15%24%14%1
2520
July1st to 10thDay
40%9%14%21%15%2
2450
11th to 20thDay
33%10%15%25%15%2
2445
21st to endDay
41%9%12%20%14%2
2511
August1st to 10thDay
40%10%14%21%15%
2314
11th to 20thDay
39%8%15%22%15%1
2174
21st to endDay
39%9%13%21%16%3
2376
September1st to 10thDay
41%8%11%19%18%3
2160
11th to 20thDay
33%6%11%24%22%3
2160
21st to endDay
45%6%9%18%21%2
1931
October1st to 10thDay
41%6%14%22%16%1
1800
11th to 20thDay
40%5%12%23%18%2
1800
21st to endDay
42%5%12%23%16%2
1949
November1st to 10thDay
35%414%25%18%4
1671
11th to 20thDay
39%6%12%23%18%2
1710
21st to endDay
39%7%13%30%9%2
1530
December1st to 10thDay
48%7%15%18%11%1
1520
11th to 20thDay
44%6%15%26%8%1
1906
21st to endDay
49%8%15%19%8%1
2772
January1st to 10thNight
41%7%14%25%11%3
4429
11th to 20thNight
44%6%14%24%10%2
4308
21st to endNight
50%5%10%25%9%1
4532
February1st to 10thNight
45%6%13%25%10%2
2470
11th to 20thNight
46%5%11%19%16%3
2241
21st to endNight
45%6%10%21%15%3
1776
March1st to 10thNight
38%6%13%24%17%3
2115
11th to 20thNight
43%5%10%22%15%4
1980
21st to endNight
43%6%10%19%18%4
2082
April1st to 10thNight
44%5%12%21%15%4
1800
11th to 20thNight
39%7%12%20%20%3
1775
21st to endNight
40%7%11%20%17%5%
1800
May1st to 10thNight
46%8%10%19%14%3
1644
11th to 20thNight
45%9%12%14%18%3
1416
21st to endNight
40%11%14%18%15%3
1551
June1st to 10thNight
39%8%11%22%19%1
1440
11th to 20thNight
38%10%15%22%14%1
1440
21st to endNight
33%9%15%26%14%2
1440
July1st to 10thNight
41%11%14%18%13%3
1400
11th to 20thNight
32%9%17%25%14%2
1392
21st to endNight
34%12%15%22%15%2
1562
August1st to 10thNight
35%10%16%22%16%1
1600
11th to 20thNight
41%9%15%17%16%2
1709
21st to endNight
36%9%14%20%18%2
1980
September1st to 10thNight
38%7%11%22%18%3
1800
11th to 20thNight
32%7%10%23%25%4
1800
21st to endNight
41%6%9%20%22%2
2023
October1st to 10thNight
42%6%12%23%15%2
2160
11th to 20thNight
37%5%12%28%16%2
2160
21st to endNight
40%5%11%26%17%2
2404
November1st to 10thNight
32%6%13%26%19%5%
2407
11th to 20thNight
40%5%10%23%18%4
2470
21st to endNight
38%5%13%28%14%1
2648
December1st to 10thNight
48%5%13%21%13%1
2660
11th to 20thNight
44%6%13%21%13%2
3288
21st to endNight
45%9%15%22%9%
4884

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
27%26%29%13%41
180
11th to 20thDay
33%25%29%10%3
216
21st to endDay
23%31%31%11%31
297
February1st to 10thDay
26%26%33%11%31
270
11th to 20thDay
28%24%37%9%1
345
21st to endDay
33%23%27%16%1
346
March1st to 10thDay
24%23%32%18%3
420
11th to 20thDay
25%29%28%14%41
420
21st to endDay
29%23%27%16%41
462
April1st to 10thDay
25%23%31%15%5%1
420
11th to 20thDay
22%23%27%18%7%3
412
21st to endDay
28%16%34%16%42
420
May1st to 10thDay
28%18%26%19%7%2
423
11th to 20thDay
23%15%31%21%8%1
447
21st to endDay
19%8%26%26%16%4
485
June1st to 10thDay
15%13%33%24%12%3
450
11th to 20thDay
18%11%30%26%13%2
450
21st to endDay
13%12%29%28%14%4
450
July1st to 10thDay
11%424%32%19%9%
445
11th to 20thDay
7%6%25%34%23%6%
444
21st to endDay
9%7%31%32%17%4
488
August1st to 10thDay
11%5%26%29%21%9%
446
11th to 20thDay
14%422%32%21%7%
439
21st to endDay
13%5%24%31%17%10%
495
September1st to 10thDay
19%9%21%25%18%8%
450
11th to 20thDay
16%5%24%28%17%10%
450
21st to endDay
21%14%25%21%16%4
450
October1st to 10thDay
24%8%24%22%17%5%
450
11th to 20thDay
18%14%31%22%14%1
450
21st to endDay
21%15%35%18%9%1
480
November1st to 10thDay
18%14%28%25%11%3
365
11th to 20thDay
19%21%31%22%6%1
370
21st to endDay
22%18%36%18%41
190
December1st to 10thDay
25%25%33%12%41
180
11th to 20thDay
28%24%32%12%31
180
21st to endDay
24%27%27%16%5%2
198
January1st to 10thNight
20%20%38%19%3
760
11th to 20thNight
25%18%30%23%3
760
21st to endNight
18%20%39%20%2
836
February1st to 10thNight
22%18%35%23%2
760
11th to 20thNight
25%22%38%14%1
722
21st to endNight
25%22%35%16%2
592
March1st to 10thNight
20%19%34%23%3
720
11th to 20thNight
24%18%34%18%5%
720
21st to endNight
20%16%38%20%5%1
792
April1st to 10thNight
23%20%33%19%4
720
11th to 20thNight
18%16%35%24%7%
711
21st to endNight
23%13%32%26%6%
720
May1st to 10thNight
24%11%30%27%8%
564
11th to 20thNight
19%10%32%33%7%
354
21st to endNight
16%6%26%38%13%1
389
June1st to 10thNight
16%8%24%36%16%
360
11th to 20thNight
13%7%27%42%11%
360
21st to endNight
11%225%48%13%1
360
July1st to 10thNight
12%320%45%19%1
350
11th to 20thNight
9%222%41%25%1
348
21st to endNight
10%419%41%24%1
474
August1st to 10thNight
11%218%41%26%2
537
11th to 20thNight
14%416%36%27%2
645
21st to endNight
14%320%36%24%2
792
September1st to 10thNight
16%425%33%20%3
720
11th to 20thNight
14%6%17%35%24%4
720
21st to endNight
20%5%21%33%20%1
720
October1st to 10thNight
23%7%23%27%16%3
720
11th to 20thNight
20%11%27%31%12%
720
21st to endNight
23%12%31%25%9%
792
November1st to 10thNight
15%11%33%29%12%1
740
11th to 20thNight
19%17%29%27%7%1
760
21st to endNight
17%17%33%26%6%
760
December1st to 10thNight
25%16%32%20%5%1
760
11th to 20thNight
19%16%35%25%4
760
21st to endNight
22%15%35%25%2
836
Page generated at 2024-02-12 06:35:31. Version ac07

Copyright 2024 Attilla Danko


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