Astrodoc's Doghouse Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Astrodoc's Doghouse Observatory clear sky chart from 2005-11-05 to 2017-09-10.

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
31%
14829
14%
46545
8%
14791
38%
14791
17%
32874

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
11%
716
9%
2434
3%
716
18%
716
7%
1976
January16th to endNight
13%
768
10%
2496
2%
768
21%
768
8%
2017
February1st to 15thNight
15%
703
9%
2287
2%
701
22%
701
8%
1830
February16th to endNight
18%
631
11%
1994
3%
631
27%
631
11%
1499
March1st to 15thNight
20%
720
13%
1992
6%
720
27%
720
15%
1502
March16th to endNight
28%
768
21%
2112
9%
768
38%
768
23%
1448
April1st to 15thNight
24%
709
15%
1833
6%
709
30%
709
20%
1330
April16th to endNight
34%
540
20%
1620
9%
540
43%
540
24%
1055
May1st to 15thNight
40%
532
17%
1612
10%
532
47%
532
23%
1078
May16th to endNight
44%
374
17%
1497
12%
374
56%
374
23%
862
June1st to 15thNight
44%
360
13%
1434
11%
360
55%
360
21%
859
June16th to endNight
45%
360
15%
1260
14%
360
54%
360
27%
740
July1st to 15thNight
61%
340
19%
1256
23%
340
67%
340
37%
635
July16th to endNight
54%
537
15%
1568
11%
504
58%
504
31%
942
August1st to 15thNight
60%
539
18%
1609
12%
536
65%
536
35%
941
August16th to endNight
58%
603
23%
1749
15%
603
63%
603
34%
1066
September1st to 15thNight
52%
700
21%
1792
11%
700
56%
700
33%
1163
September16th to endNight
50%
657
20%
1817
14%
657
54%
657
30%
1141
October1st to 15thNight
38%
660
18%
1980
14%
660
44%
660
22%
1345
October16th to endNight
23%
704
13%
2112
6%
704
31%
704
14%
1565
November1st to 15thNight
31%
700
17%
2363
13%
700
37%
700
18%
1599
November16th to endNight
20%
720
10%
2520
6%
720
26%
720
10%
1920
December1st to 15thNight
11%
720
6%
2520
2%
720
16%
720
7%
2060
December16th to endNight
9%
768
6%
2688
1%
768
14%
768
5%
2301

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%9%47%6%35%5%5%7%30%
48077
Night
15%9%47%5%3445%6%33%
46723
Cloud CoverDay
15%9%47%6%35%45%7%30%
48087
Night
15%9%47%5%3445%6%33%
46727
TransparencyDay
52%7%11%18%9%
47773
Night
50%6%11%19%10%1
46545
SeeingDay
18%10%27%23%13%6%
5571
Night
19%12%30%25%11%1
14835

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
19%16%6%10%7%45%435%16%
1504
16th to endDay
12%16%8%12%9%5%444415%
1728
February1st to 15thDay
16%15%6%11%7%5%6%45%5%15%
1575
16th to endDay
17%14%5%8%8%46%45%6%18%
1479
March1st to 15thDay
15%12%5%8%7%36%345%25%
1957
16th to endDay
15%9%47%6%35%45%6%32%
2112
April1st to 15thDay
20%10%46%43445%5%29%
2123
16th to endDay
18%9%35%423346%37%
2340
May1st to 15thDay
17%8%25%5%245%5%7%35%
2337
16th to endDay
12%6%35%7%35%5%5%7%38%
2618
June1st to 15thDay
15%6%35%435%5%6%8%36%
2523
16th to endDay
13%5%25%6%35%5%6%10%36%
2700
July1st to 15thDay
9%425%6%35%6%6%9%39%
2625
16th to endDay
10%5%35%5%45%6%7%9%35%
2491
August1st to 15thDay
10%5%26%7%45%7%6%7%36%
2340
16th to endDay
12%6%36%5%35%5%6%9%36%
2441
September1st to 15thDay
14%6%26%5%3445%8%37%
2054
16th to endDay
15%6%245%2446%7%38%
1812
October1st to 15thDay
20%8%36%5%35%345%32%
1650
16th to endDay
26%11%47%5%3445%5%22%
1760
November1st to 15thDay
16%10%37%5%345%5%7%30%
1492
16th to endDay
19%13%8%10%6%3445%5%20%
1440
December1st to 15thDay
16%17%6%12%6%36%5%46%13%
1440
16th to endDay
20%17%8%11%8%35%43312%
1536
January1st to 15thNight
21%13%6%10%6%44445%17%
2434
16th to endNight
14%13%7%11%8%45%445%18%
2496
February1st to 15thNight
15%13%6%9%8%35%5%5%5%20%
2285
16th to endNight
15%11%5%9%7%35%5%5%6%24%
1994
March1st to 15thNight
16%9%5%6%7%45%5%5%5%28%
1980
16th to endNight
14%9%45%424345%40%
2112
April1st to 15thNight
19%9%34434446%34%
1833
16th to endNight
12%6%26%6%3445%6%41%
1620
May1st to 15thNight
14%6%26%5%25%45%7%39%
1612
16th to endNight
10%425%5%3445%7%46%
1495
June1st to 15thNight
11%5%24435%47%8%41%
1434
16th to endNight
10%425%5%3435%8%46%
1260
July1st to 15thNight
5%32432345%9%56%
1332
16th to endNight
8%425%425%46%9%47%
1675
August1st to 15thNight
6%3235%335%6%9%49%
1620
16th to endNight
8%5%2443435%6%51%
1749
September1st to 15thNight
12%41343445%7%48%
1792
16th to endNight
12%5%2442445%8%45%
1817
October1st to 15thNight
16%6%26%5%235%37%39%
1980
16th to endNight
20%9%37%6%34447%28%
2112
November1st to 15thNight
14%8%36%6%345%5%8%33%
2363
16th to endNight
19%11%48%445%446%24%
2520
December1st to 15thNight
20%15%5%8%6%35%45%5%17%
2520
16th to endNight
20%14%8%11%7%35%45%5%12%
2688

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
19%15%7%10%7%5%4345%16%
1504
16th to endDay
12%17%8%13%9%5%444414%
1728
February1st to 15thDay
16%15%6%12%7%46%5%5%5%15%
1575
16th to endDay
17%14%5%10%7%45%45%5%18%
1479
March1st to 15thDay
16%12%5%9%6%36%345%26%
1968
16th to endDay
15%9%47%6%34446%32%
2111
April1st to 15thDay
20%10%45%43445%6%29%
2123
16th to endDay
18%10%35%5%23346%37%
2340
May1st to 15thDay
17%8%36%5%2345%7%34%
2337
16th to endDay
12%6%36%5%35%45%8%38%
2618
June1st to 15thDay
15%6%25%435%5%6%8%36%
2523
16th to endDay
13%5%25%5%35%5%6%9%35%
2700
July1st to 15thDay
8%425%6%36%5%7%9%38%
2625
16th to endDay
10%6%35%6%45%6%7%9%35%
2491
August1st to 15thDay
10%6%25%7%46%6%6%7%35%
2340
16th to endDay
11%6%37%5%35%5%6%9%35%
2441
September1st to 15thDay
15%6%26%5%335%5%8%36%
2054
16th to endDay
15%6%25%42445%8%38%
1812
October1st to 15thDay
19%9%36%5%3444433%
1650
16th to endDay
26%11%46%6%33445%21%
1760
November1st to 15thDay
15%11%37%5%246%6%6%29%
1492
16th to endDay
19%15%7%8%6%2445%6%19%
1440
December1st to 15thDay
17%18%7%10%7%35%45%6%13%
1440
16th to endDay
20%16%9%11%7%35%44312%
1536
January1st to 15thNight
21%13%6%9%7%34445%17%
2434
16th to endNight
14%13%8%11%8%44446%17%
2496
February1st to 15thNight
14%14%5%10%9%35%5%5%5%20%
2278
16th to endNight
15%11%6%9%7%345%5%6%24%
1994
March1st to 15thNight
17%9%5%6%6%45%45%5%28%
1992
16th to endNight
15%9%46%42434440%
2112
April1st to 15thNight
19%9%445%24446%34%
1833
16th to endNight
12%6%36%6%33446%41%
1620
May1st to 15thNight
14%6%26%425%45%7%38%
1611
16th to endNight
10%425%5%3445%7%46%
1495
June1st to 15thNight
11%5%24435%5%6%8%40%
1434
16th to endNight
10%5%245%35%25%8%46%
1260
July1st to 15thNight
5%31333345%9%56%
1332
16th to endNight
8%5%2443447%8%47%
1675
August1st to 15thNight
6%4144345%6%9%50%
1620
16th to endNight
8%42443435%7%50%
1749
September1st to 15thNight
11%42442446%6%47%
1792
16th to endNight
13%6%2443346%8%44%
1817
October1st to 15thNight
16%6%36%5%23437%39%
1980
16th to endNight
21%9%37%5%3445%6%28%
2112
November1st to 15thNight
14%8%36%5%345%5%8%34%
2363
16th to endNight
20%11%48%5%26%447%23%
2520
December1st to 15thNight
20%15%6%9%6%345%5%5%17%
2520
16th to endNight
21%14%9%11%7%3445%5%12%
2688

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
70%5%8%9%4
1505
16th to endDay
72%5%8%7%6%
1728
February1st to 15thDay
69%6%7%11%3
1577
16th to endDay
66%48%12%6%1
1479
March1st to 15thDay
60%5%10%14%7%
1968
16th to endDay
52%6%10%17%11%1
2112
April1st to 15thDay
54%5%9%18%10%
2123
16th to endDay
48%49%20%14%2
2340
May1st to 15thDay
48%6%10%22%11%
2337
16th to endDay
43%7%13%20%13%1
2622
June1st to 15thDay
43%8%12%22%12%
2523
16th to endDay
42%7%14%22%12%
2700
July1st to 15thDay
37%8%12%23%16%1
2472
16th to endDay
41%9%14%21%10%2
2335
August1st to 15thDay
43%9%14%19%11%1
2327
16th to endDay
42%7%14%23%10%
2441
September1st to 15thDay
44%6%15%23%9%
2054
16th to endDay
42%8%12%27%9%
1812
October1st to 15thDay
53%5%11%16%11%1
1650
16th to endDay
63%6%12%12%4
1760
November1st to 15thDay
52%7%14%16%8%
1492
16th to endDay
65%5%10%12%5%
1440
December1st to 15thDay
70%8%10%8%2
1440
16th to endDay
76%5%6%8%2
1536
January1st to 15thNight
68%5%9%11%5%
2434
16th to endNight
66%6%9%11%5%
2496
February1st to 15thNight
64%7%9%14%4
2287
16th to endNight
58%5%12%14%7%
1994
March1st to 15thNight
55%5%11%18%7%
1992
16th to endNight
46%48%21%15%2
2112
April1st to 15thNight
50%49%19%13%
1833
16th to endNight
43%5%8%21%18%3
1620
May1st to 15thNight
45%5%9%24%13%2
1612
16th to endNight
36%7%12%26%13%3
1497
June1st to 15thNight
38%7%11%25%15%1
1434
16th to endNight
36%6%14%26%16%
1260
July1st to 15thNight
24%6%11%31%23%2
1256
16th to endNight
33%7%14%25%16%2
1568
August1st to 15thNight
28%8%17%30%12%2
1609
16th to endNight
32%6%10%30%17%1
1749
September1st to 15thNight
34%7%13%29%14%
1792
16th to endNight
35%7%12%29%14%1
1817
October1st to 15thNight
45%6%10%23%13%
1980
16th to endNight
55%5%13%17%6%
2112
November1st to 15thNight
46%6%14%18%11%1
2363
16th to endNight
60%5%13%13%6%
2520
December1st to 15thNight
67%7%11%10%3
2520
16th to endNight
72%6%8%8%2
2688

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
20%19%43%12%4
72
16th to endDay
28%14%41%15%
96
February1st to 15thDay
25%24%38%10%1
90
16th to endDay
27%23%39%8%1
81
March1st to 15thDay
24%15%31%22%5%
258
16th to endDay
23%10%31%25%6%2
288
April1st to 15thDay
23%16%28%20%10%
270
16th to endDay
20%12%32%18%12%4
270
May1st to 15thDay
21%8%27%24%11%6%
288
16th to endDay
15%10%32%22%12%7%
331
June1st to 15thDay
17%10%24%30%14%3
318
16th to endDay
15%8%30%29%12%3
495
July1st to 15thDay
9%5%27%30%18%7%
406
16th to endDay
11%5%26%26%21%9%
326
August1st to 15thDay
11%320%28%23%12%
313
16th to endDay
17%316%23%22%16%
332
September1st to 15thDay
12%5%18%28%22%12%
294
16th to endDay
19%6%18%23%20%11%
254
October1st to 15thDay
17%13%25%21%16%5%
255
16th to endDay
30%14%26%22%5%
272
November1st to 15thDay
15%12%38%20%8%3
78
16th to endDay
28%18%30%13%5%5%
60
December1st to 15thDay
33%25%28%11%1
60
16th to endDay
39%18%39%3
64
January1st to 15thNight
27%20%34%15%2
720
16th to endNight
22%16%37%18%4
768
February1st to 15thNight
21%21%33%20%3
704
16th to endNight
20%17%35%20%5%
631
March1st to 15thNight
22%16%34%20%4
720
16th to endNight
19%12%33%23%9%
768
April1st to 15thNight
24%15%32%23%5%
709
16th to endNight
15%10%32%30%10%1
540
May1st to 15thNight
17%7%28%30%14%1
532
16th to endNight
12%433%32%17%
375
June1st to 15thNight
14%5%28%36%13%
360
16th to endNight
11%332%38%13%
360
July1st to 15thNight
3425%45%20%1
340
16th to endNight
11%124%39%20%2
537
August1st to 15thNight
7%221%40%25%2
539
16th to endNight
11%320%33%27%3
603
September1st to 15thNight
13%6%23%30%21%5%
700
16th to endNight
16%5%21%28%23%5%
657
October1st to 15thNight
20%8%26%26%15%2
660
16th to endNight
25%14%31%22%5%
704
November1st to 15thNight
18%12%32%23%10%1
700
16th to endNight
26%19%28%18%6%
720
December1st to 15thNight
29%18%32%15%3
720
16th to endNight
29%19%33%14%2
768
Page generated at 2017-09-11 19:35:13. Version ac04

Copyright 2017 A. Danko


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