Doghouse Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Doghouse Observatory clear sky chart from 2005-11-05 to 2017-10-06.

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
21%
14988
12%
46904
5%
14943
30%
14943
14%
34088

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
14%
750
12%
2658
1%
746
28%
746
10%
1912
January16th to endNight
16%
777
15%
2547
3%
777
31%
777
13%
1779
February1st to 15thNight
15%
704
10%
2286
3%
701
25%
701
13%
1669
February16th to endNight
16%
631
11%
2050
3%
631
26%
631
10%
1539
March1st to 15thNight
17%
719
14%
1989
4%
719
26%
719
14%
1515
March16th to endNight
19%
768
15%
2112
6%
768
27%
768
16%
1581
April1st to 15thNight
19%
543
12%
1788
6%
543
26%
543
12%
1339
April16th to endNight
25%
540
15%
1620
7%
540
32%
540
18%
1159
May1st to 15thNight
26%
540
11%
1500
5%
540
32%
540
17%
1122
May16th to endNight
19%
561
10%
1496
3%
560
26%
560
19%
1101
June1st to 15thNight
27%
429
7%
1329
4%
429
29%
429
15%
1001
June16th to endNight
28%
360
7%
1260
3%
360
34%
360
16%
904
July1st to 15thNight
35%
340
12%
1190
8%
340
41%
340
23%
745
July16th to endNight
28%
551
9%
1422
5%
518
31%
518
20%
1030
August1st to 15thNight
37%
539
10%
1608
5%
535
40%
535
21%
1123
August16th to endNight
37%
573
14%
1767
7%
573
43%
573
25%
1139
September1st to 15thNight
29%
540
17%
1800
10%
540
39%
540
24%
1123
September16th to endNight
32%
704
22%
2003
12%
704
42%
704
25%
1278
October1st to 15thNight
26%
684
17%
2050
8%
684
34%
684
21%
1381
October16th to endNight
16%
705
12%
2119
4%
705
24%
705
12%
1624
November1st to 15thNight
18%
730
11%
2453
5%
730
25%
730
11%
1855
November16th to endNight
19%
750
11%
2520
4%
750
28%
750
10%
1900
December1st to 15thNight
10%
750
11%
2520
1%
750
21%
750
7%
1992
December16th to endNight
8%
800
8%
2817
1%
800
17%
800
5%
2277

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
19%9%36%5%3445%6%30%
48302
Night
19%10%36%5%34446%30%
47067
TransparencyDay
53%412%20%8%
47983
Night
54%411%19%8%
46904
SeeingDay
24%14%31%20%7%1
7357
Night
25%15%31%20%6%
14989

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
15%14%410%6%33335%29%
1278
16th to endDay
13%10%48%7%24446%31%
1674
February1st to 15thDay
15%11%5%8%6%25%446%29%
1575
16th to endDay
14%14%6%8%6%3445%7%25%
1422
March1st to 15thDay
17%11%5%9%6%23446%28%
1960
16th to endDay
16%13%6%7%433335%30%
2112
April1st to 15thDay
18%11%5%6%6%35%446%27%
2157
16th to endDay
22%9%35%43445%6%31%
2340
May1st to 15thDay
24%8%37%5%34445%29%
2450
16th to endDay
24%9%36%5%2345%6%28%
2618
June1st to 15thDay
27%8%27%5%33445%25%
2640
16th to endDay
22%7%36%42445%7%29%
2700
July1st to 15thDay
13%5%25%6%25%6%6%8%36%
2700
16th to endDay
15%6%36%7%35%5%6%8%30%
2636
August1st to 15thDay
17%6%25%5%35%46%8%33%
2340
16th to endDay
13%5%25%4345%6%8%40%
2435
September1st to 15thDay
19%5%25%3245%47%38%
2160
16th to endDay
18%5%2442235%7%42%
1956
October1st to 15thDay
19%7%25%42435%6%37%
1708
16th to endDay
24%10%26%6%34446%26%
1752
November1st to 15thDay
23%12%36%5%33435%28%
1405
16th to endDay
17%14%5%7%6%35%5%5%5%24%
1440
December1st to 15thDay
22%12%5%7%6%35%345%21%
1440
16th to endDay
22%16%5%6%6%24345%20%
1404
January1st to 15thNight
16%12%5%6%6%4435%5%29%
2658
16th to endNight
15%11%36%5%3445%5%33%
2547
February1st to 15thNight
18%12%37%5%34446%27%
2285
16th to endNight
16%15%5%8%7%25%44425%
2050
March1st to 15thNight
19%10%48%6%35%345%28%
1977
16th to endNight
19%13%6%7%42433431%
2112
April1st to 15thNight
21%12%46%5%35%345%26%
1788
16th to endNight
23%10%35%433335%33%
1620
May1st to 15thNight
25%7%36%4345%45%28%
1500
16th to endNight
21%8%26%5%34447%31%
1494
June1st to 15thNight
27%7%35%5%3445%7%24%
1329
16th to endNight
20%9%34435%5%5%7%30%
1260
July1st to 15thNight
12%7%25%5%345%6%11%34%
1260
16th to endNight
16%6%37%7%35%45%9%30%
1518
August1st to 15thNight
16%6%37%6%35%5%5%5%33%
1620
16th to endNight
14%5%25%43446%9%38%
1767
September1st to 15thNight
18%6%24323347%43%
1800
16th to endNight
14%5%25%423346%44%
2003
October1st to 15thNight
18%6%26%5%24446%38%
2050
16th to endNight
28%8%36%434245%27%
2119
November1st to 15thNight
22%12%36%6%23345%27%
2453
16th to endNight
20%12%46%5%345%5%5%28%
2520
December1st to 15thNight
21%12%47%7%4445%423%
2520
16th to endNight
25%15%5%7%5%2334321%
2817

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
59%5%10%13%10%1
1279
16th to endDay
54%49%17%13%
1674
February1st to 15thDay
56%311%19%8%1
1578
16th to endDay
58%311%16%8%1
1422
March1st to 15thDay
58%211%18%9%1
1971
16th to endDay
57%39%19%8%1
2112
April1st to 15thDay
56%38%17%11%2
2157
16th to endDay
52%310%19%11%1
2340
May1st to 15thDay
57%38%20%9%
2450
16th to endDay
56%412%19%6%
2622
June1st to 15thDay
58%411%17%6%
2640
16th to endDay
54%413%20%6%
2700
July1st to 15thDay
40%6%16%25%10%
2541
16th to endDay
48%5%18%20%6%
2470
August1st to 15thDay
45%6%15%25%7%
2327
16th to endDay
39%5%19%27%8%
2435
September1st to 15thDay
45%415%23%10%
2160
16th to endDay
41%311%28%12%1
1956
October1st to 15thDay
48%212%26%8%
1708
16th to endDay
59%410%18%7%
1752
November1st to 15thDay
58%414%13%8%
1405
16th to endDay
60%7%11%12%7%
1440
December1st to 15thDay
65%7%9%14%2
1440
16th to endDay
66%5%8%11%7%
1404
January1st to 15thNight
55%5%11%16%9%
2658
16th to endNight
52%411%22%9%
2547
February1st to 15thNight
56%311%16%11%
2286
16th to endNight
60%39%14%9%1
2050
March1st to 15thNight
58%39%17%9%1
1989
16th to endNight
57%37%19%11%1
2112
April1st to 15thNight
60%38%14%11%1
1788
16th to endNight
54%29%18%13%1
1620
May1st to 15thNight
55%411%20%7%1
1500
16th to endNight
52%5%14%19%6%
1496
June1st to 15thNight
58%411%17%7%
1329
16th to endNight
52%7%13%19%7%
1260
July1st to 15thNight
41%5%18%26%7%
1190
16th to endNight
51%5%17%17%8%
1422
August1st to 15thNight
49%416%22%7%
1608
16th to endNight
41%5%18%26%6%
1767
September1st to 15thNight
41%412%30%11%
1800
16th to endNight
41%313%28%12%
2003
October1st to 15thNight
46%412%26%9%
2050
16th to endNight
59%48%17%9%
2119
November1st to 15thNight
60%312%14%7%
2453
16th to endNight
58%6%12%15%6%
2520
December1st to 15thNight
63%6%9%16%4
2520
16th to endNight
67%5%7%12%6%
2817

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
23%27%38%8%2
85
16th to endDay
18%17%42%16%31
256
February1st to 15thDay
21%18%35%18%5%
236
16th to endDay
26%16%32%18%5%
212
March1st to 15thDay
21%24%32%16%31
269
16th to endDay
26%20%32%16%31
288
April1st to 15thDay
27%24%29%14%3
270
16th to endDay
23%22%29%16%6%1
270
May1st to 15thDay
33%13%24%17%8%2
406
16th to endDay
29%13%30%21%4
519
June1st to 15thDay
35%10%27%19%6%1
495
16th to endDay
25%7%35%23%6%1
495
July1st to 15thDay
16%8%38%25%9%1
475
16th to endDay
22%431%29%11%1
494
August1st to 15thDay
19%7%28%29%14%1
313
16th to endDay
16%8%28%29%13%3
332
September1st to 15thDay
18%10%37%24%7%
315
16th to endDay
23%8%33%24%6%2
305
October1st to 15thDay
20%14%30%20%10%2
243
16th to endDay
27%27%25%13%4
240
November1st to 15thDay
31%16%26%14%8%1
235
16th to endDay
27%20%31%12%7%
240
December1st to 15thDay
28%24%31%13%2
240
16th to endDay
21%28%37%10%1
124
January1st to 15thNight
22%24%30%18%3
750
16th to endNight
22%19%36%15%4
777
February1st to 15thNight
24%17%36%16%3
704
16th to endNight
26%18%29%17%5%1
631
March1st to 15thNight
24%18%32%20%4
720
16th to endNight
26%17%27%19%7%1
768
April1st to 15thNight
29%13%30%20%5%
543
16th to endNight
29%11%29%22%7%
540
May1st to 15thNight
29%12%26%22%7%1
540
16th to endNight
24%14%33%21%5%
561
June1st to 15thNight
31%6%30%26%5%
429
16th to endNight
21%5%34%27%9%1
360
July1st to 15thNight
15%5%38%29%10%
340
16th to endNight
18%5%36%28%10%
551
August1st to 15thNight
18%431%29%14%
539
16th to endNight
16%6%33%31%10%
573
September1st to 15thNight
21%9%35%25%7%
540
16th to endNight
17%13%31%26%9%
704
October1st to 15thNight
21%13%33%20%10%
684
16th to endNight
33%19%27%15%3
705
November1st to 15thNight
32%14%28%17%6%1
730
16th to endNight
27%22%26%18%5%
750
December1st to 15thNight
29%23%30%13%3
750
16th to endNight
32%21%28%12%41
800
Page generated at 2017-10-07 15:07:52. Version ac04

Copyright 2017 A. Danko


Doghouse Observatory Clear Sky Chart | Charts Home