Strawberry Point Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Strawberry Point 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
53%
24154
31%
79410
21%
24059
64%
24059
40%
39039

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
44%
752
33%
4010
19%
736
60%
736
25%
1802
January11th to 20thNight
47%
758
33%
3992
23%
740
63%
740
27%
1717
January21st to endNight
42%
828
22%
4263
19%
814
60%
814
20%
2167
February1st to 10thNight
37%
760
27%
2447
16%
760
53%
760
33%
1298
February11th to 20thNight
39%
718
31%
2152
20%
718
56%
718
36%
1157
February21st to endNight
38%
592
30%
1776
19%
592
52%
592
30%
1016
March1st to 10thNight
39%
720
26%
2050
15%
720
53%
720
34%
1163
March11th to 20thNight
47%
720
30%
1980
19%
720
57%
720
38%
1098
March21st to endNight
36%
792
27%
2178
10%
792
51%
792
35%
1200
April1st to 10thNight
39%
720
28%
1980
12%
720
51%
720
37%
1060
April11th to 20thNight
37%
600
34%
1699
13%
600
54%
600
40%
833
April21st to endNight
37%
540
34%
1620
14%
540
55%
540
38%
786
May1st to 10thNight
40%
540
33%
1620
15%
540
54%
540
43%
794
May11th to 20thNight
54%
531
35%
1595
22%
531
63%
531
49%
731
May21st to endNight
47%
582
28%
1746
16%
582
57%
582
42%
854
June1st to 10thNight
60%
540
32%
1620
23%
540
69%
540
60%
699
June11th to 20thNight
55%
540
32%
1620
24%
540
64%
540
59%
698
June21st to endNight
66%
540
31%
1620
25%
540
72%
540
64%
690
July1st to 10thNight
76%
525
28%
1575
23%
525
80%
525
57%
738
July11th to 20thNight
74%
522
22%
1566
21%
522
75%
522
41%
858
July21st to endNight
75%
591
21%
1674
19%
558
75%
558
35%
970
August1st to 10thNight
75%
537
29%
1602
21%
534
78%
534
49%
787
August11th to 20thNight
79%
534
35%
1602
27%
534
82%
534
52%
769
August21st to endNight
78%
674
36%
1878
28%
674
80%
674
55%
936
September1st to 10thNight
75%
720
33%
1980
25%
720
79%
720
52%
1014
September11th to 20thNight
69%
720
39%
1980
27%
720
77%
720
57%
955
September21st to endNight
67%
720
40%
1980
27%
720
76%
720
61%
921
October1st to 10thNight
54%
720
34%
2002
20%
720
65%
720
47%
1031
October11th to 20thNight
60%
720
41%
2160
27%
720
74%
720
57%
959
October21st to endNight
55%
792
41%
2376
26%
792
71%
792
49%
1057
November1st to 10thNight
54%
740
35%
2373
23%
740
69%
740
48%
1070
November11th to 20thNight
53%
760
38%
2470
28%
760
68%
760
52%
1046
November21st to endNight
50%
760
35%
2470
25%
760
65%
760
41%
1169
December1st to 10thNight
49%
760
31%
2470
22%
760
62%
760
38%
1246
December11th to 20thNight
45%
760
30%
2911
19%
758
59%
758
29%
1555
December21st to endNight
35%
826
17%
4373
15%
817
51%
817
18%
2195

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
35%2443445%7%57%
78793
Night
35%2432445%7%62%
80356
TransparencyDay
24%5%9%19%26%17%
78520
Night
21%5%9%20%27%17%
80151
SeeingDay
9%19%30%26%13%4
13912
Night
6%13%24%30%23%5%
24188

By Month

Percentage Cloud Cover SW (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
25%35%4345%5%8%57%
2858
11th to 20thDay
26%2342435%9%60%
2860
21st to endDay
412%45%323346%54%
3146
February1st to 10thDay
210%3432435%7%56%
1729
11th to 20thDay
48%3443445%7%56%
1791
21st to endDay
39%47%323347%53%
1480
March1st to 10thDay
47%35%435%5%5%7%53%
1908
11th to 20thDay
39%445%345%6%8%49%
1980
21st to endDay
39%35%4345%7%8%47%
2178
April1st to 10thDay
37%244245%5%7%56%
1980
11th to 20thDay
25%25%33446%8%58%
2204
21st to endDay
45%245%2445%7%59%
2340
May1st to 10thDay
45%35%4345%6%7%54%
2340
11th to 20thDay
35%2442448%8%56%
2301
21st to endDay
45%25%5%3445%7%55%
2530
June1st to 10thDay
121332345%7%68%
2340
11th to 20thDay
3223323335%72%
2340
21st to endDay
231332445%6%68%
2340
July1st to 10thDay
33245%45%5%6%6%57%
2340
11th to 20thDay
34246%46%6%7%9%48%
2340
21st to endDay
6%5%37%8%48%8%7%8%36%
2545
August1st to 10thDay
44247%35%6%5%8%53%
2328
11th to 20thDay
43246%346%6%8%55%
2299
21st to endDay
5%325%6%35%5%6%7%54%
2471
September1st to 10thDay
45%25%5%35%5%46%55%
1980
11th to 20thDay
4323433346%66%
1980
21st to endDay
4213423445%67%
1980
October1st to 10thDay
7%424325%346%60%
1958
11th to 20thDay
431231333473%
1800
21st to endDay
321232334473%
1980
November1st to 10thDay
3423223346%68%
1702
11th to 20thDay
2322224346%70%
1710
21st to endDay
36%2442345%8%61%
1710
December1st to 10thDay
28%24423446%60%
1710
11th to 20thDay
6%9%35%5%25%45%7%49%
2169
21st to endDay
5%7%243345%6%9%51%
3146
January1st to 10thNight
37%25%424445%60%
4097
11th to 20thNight
14244245%5%7%63%
4110
21st to endNight
410%35%324445%56%
4521
February1st to 10thNight
29%34424347%58%
2447
11th to 20thNight
29%34434347%58%
2151
21st to endNight
39%46%5%24346%54%
1776
March1st to 10thNight
38%36%4245%6%7%52%
2050
11th to 20thNight
37%34435%5%6%8%53%
1980
21st to endNight
35%24435%47%6%57%
2178
April1st to 10thNight
342433445%7%63%
1980
11th to 20thNight
23133235%5%8%64%
1699
21st to endNight
34133235%5%8%63%
1620
May1st to 10thNight
4323434448%63%
1620
11th to 20thNight
221233335%7%68%
1594
21st to endNight
3324323447%64%
1746
June1st to 10thNight
211332235%8%70%
1620
11th to 20thNight
1112322336%74%
1620
21st to endNight
1213313445%73%
1620
July1st to 10thNight
221332446%7%66%
1620
11th to 20thNight
3324436%5%6%10%53%
1620
21st to endNight
25%25%6%36%8%8%11%44%
1773
August1st to 10thNight
2323435%448%63%
1611
11th to 20thNight
32134245%6%9%62%
1602
21st to endNight
321332347%6%66%
1878
September1st to 10thNight
5%32332445%6%64%
1980
11th to 20thNight
4313212345%72%
1980
21st to endNight
421231222477%
1980
October1st to 10thNight
6%313323445%67%
2002
11th to 20thNight
331221133477%
2160
21st to endNight
231231335%6%72%
2376
November1st to 10thNight
2423323347%68%
2373
11th to 20thNight
2312314346%70%
2470
21st to endNight
36%24323347%65%
2470
December1st to 10thNight
37%3332335%7%61%
2470
11th to 20thNight
5%7%243345%6%9%52%
3041
21st to endNight
37%36%5%345%5%7%52%
4521

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
25%7%15%25%24%3
2859
11th to 20thDay
22%6%17%27%20%8%
2860
21st to endDay
32%48%28%23%4
3146
February1st to 10thDay
27%413%22%24%9%
1729
11th to 20thDay
28%49%21%26%12%
1801
21st to endDay
32%49%18%27%9%
1480
March1st to 10thDay
29%5%9%23%27%8%
1908
11th to 20thDay
29%5%10%26%22%7%
1980
21st to endDay
31%6%12%23%22%6%
2178
April1st to 10thDay
25%5%9%23%25%13%
1980
11th to 20thDay
22%48%23%29%14%
2207
21st to endDay
22%48%24%32%9%
2340
May1st to 10thDay
25%49%19%31%11%
2340
11th to 20thDay
22%5%11%21%29%13%
2304
21st to endDay
25%5%8%17%33%13%
2530
June1st to 10thDay
13%27%16%36%25%
2340
11th to 20thDay
14%35%9%26%42%
2340
21st to endDay
15%3310%25%44%
2340
July1st to 10thDay
22%47%10%19%37%
2276
11th to 20thDay
26%8%12%15%21%18%
2271
21st to endDay
35%10%14%16%13%11%
2404
August1st to 10thDay
26%6%11%14%16%27%
2313
11th to 20thDay
22%5%11%13%21%27%
2299
21st to endDay
25%5%8%18%24%20%
2471
September1st to 10thDay
25%6%8%12%21%29%
1980
11th to 20thDay
19%37%18%24%30%
1980
21st to endDay
18%46%13%34%25%
1980
October1st to 10thDay
23%5%7%18%24%23%
1958
11th to 20thDay
15%25%17%35%26%
1800
21st to endDay
14%46%21%38%17%
1980
November1st to 10thDay
18%36%24%34%15%
1702
11th to 20thDay
16%48%24%33%15%
1710
21st to endDay
22%49%20%31%15%
1710
December1st to 10thDay
26%5%11%20%28%10%
1710
11th to 20thDay
33%7%11%20%20%8%
2168
21st to endDay
27%7%12%19%26%8%
3146
January1st to 10thNight
25%6%11%27%26%5%
4097
11th to 20thNight
23%6%14%32%20%6%
4110
21st to endNight
30%6%9%25%23%6%
4521
February1st to 10thNight
27%410%24%23%11%
2447
11th to 20thNight
26%47%18%27%17%
2152
21st to endNight
31%48%18%28%9%
1776
March1st to 10thNight
28%5%9%23%27%9%
2050
11th to 20thNight
26%5%9%28%24%9%
1980
21st to endNight
24%5%12%26%24%8%
2178
April1st to 10thNight
22%5%7%26%26%14%
1980
11th to 20thNight
18%49%24%32%14%
1699
21st to endNight
19%48%22%37%10%
1620
May1st to 10thNight
20%48%20%36%12%
1620
11th to 20thNight
15%5%6%24%34%16%
1595
21st to endNight
20%47%17%36%15%
1746
June1st to 10thNight
12%36%13%40%27%
1620
11th to 20thNight
10%46%10%25%45%
1620
21st to endNight
11%348%25%48%
1620
July1st to 10thNight
14%6%7%11%19%43%
1575
11th to 20thNight
25%8%10%16%19%23%
1566
21st to endNight
29%8%16%22%12%12%
1674
August1st to 10thNight
20%412%16%19%29%
1602
11th to 20thNight
17%5%10%14%21%32%
1602
21st to endNight
18%48%17%26%26%
1878
September1st to 10thNight
18%5%8%15%22%31%
1980
11th to 20thNight
15%46%16%24%35%
1980
21st to endNight
13%36%14%35%30%
1980
October1st to 10thNight
20%5%6%18%27%24%
2002
11th to 20thNight
13%35%15%36%28%
2160
21st to endNight
13%47%18%39%19%
2376
November1st to 10thNight
16%410%23%32%15%
2373
11th to 20thNight
14%39%22%36%16%
2470
21st to endNight
21%37%17%35%17%
2470
December1st to 10thNight
24%411%23%24%14%
2470
11th to 20thNight
27%7%12%21%25%9%
3041
21st to endNight
31%7%12%14%24%13%
4521

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
14%27%29%19%10%2
270
11th to 20thDay
13%24%28%23%9%2
270
21st to endDay
9%23%28%26%13%2
297
February1st to 10thDay
11%31%29%17%9%3
289
11th to 20thDay
15%24%35%19%6%1
432
21st to endDay
13%34%32%18%21
346
March1st to 10thDay
16%29%30%15%10%1
420
11th to 20thDay
10%26%35%20%9%1
420
21st to endDay
15%33%34%14%4
462
April1st to 10thDay
8%28%37%16%9%2
420
11th to 20thDay
14%33%32%15%5%1
412
21st to endDay
12%29%28%20%8%2
420
May1st to 10thDay
13%27%35%16%7%1
423
11th to 20thDay
8%20%33%25%9%4
448
21st to endDay
10%22%32%22%10%3
485
June1st to 10thDay
414%37%32%11%2
450
11th to 20thDay
5%14%40%26%12%3
450
21st to endDay
410%37%33%13%3
450
July1st to 10thDay
36%28%41%17%5%
446
11th to 20thDay
45%24%38%22%8%
444
21st to endDay
7%317%41%24%7%
487
August1st to 10thDay
5%6%28%38%17%6%
447
11th to 20thDay
7%6%27%34%19%8%
437
21st to endDay
45%31%33%19%8%
495
September1st to 10thDay
410%26%30%22%9%
450
11th to 20thDay
5%14%31%28%16%5%
450
21st to endDay
6%15%25%31%17%6%
450
October1st to 10thDay
8%23%28%21%14%6%
428
11th to 20thDay
10%16%22%27%18%7%
270
21st to endDay
10%21%26%25%16%1
297
November1st to 10thDay
7%25%27%24%15%3
270
11th to 20thDay
419%32%25%14%5%
270
21st to endDay
9%22%23%24%19%4
270
December1st to 10thDay
6%22%33%21%17%1
270
11th to 20thDay
7%24%30%23%12%4
270
21st to endDay
15%26%31%19%8%1
297
January1st to 10thNight
8%17%26%24%18%8%
760
11th to 20thNight
7%15%28%28%17%5%
760
21st to endNight
8%15%29%28%16%4
836
February1st to 10thNight
9%17%32%26%14%3
760
11th to 20thNight
8%16%32%28%12%3
722
21st to endNight
9%20%28%28%11%3
592
March1st to 10thNight
9%19%31%27%13%2
720
11th to 20thNight
7%16%26%28%22%3
720
21st to endNight
7%22%31%27%11%3
792
April1st to 10thNight
5%23%29%24%16%2
720
11th to 20thNight
6%24%31%24%13%3
600
21st to endNight
7%24%29%24%14%3
540
May1st to 10thNight
6%13%36%30%12%2
540
11th to 20thNight
313%26%32%23%4
531
21st to endNight
5%15%28%29%21%2
584
June1st to 10thNight
29%24%41%21%2
540
11th to 20thNight
210%29%35%21%4
540
21st to endNight
25%23%40%26%4
540
July1st to 10thNight
216%36%40%6%
525
11th to 20thNight
2111%36%40%8%
522
21st to endNight
416%34%49%8%
591
August1st to 10thNight
4112%39%38%7%
537
11th to 20thNight
328%36%45%6%
534
21st to endNight
4211%34%39%11%
674
September1st to 10thNight
5%410%31%39%10%
720
11th to 20thNight
45%16%33%33%9%
720
21st to endNight
5%8%16%29%32%10%
720
October1st to 10thNight
8%10%24%31%22%5%
720
11th to 20thNight
410%22%32%23%8%
720
21st to endNight
418%19%28%24%7%
792
November1st to 10thNight
412%25%30%21%7%
740
11th to 20thNight
413%27%29%20%7%
760
21st to endNight
8%15%23%27%22%5%
760
December1st to 10thNight
7%14%26%29%20%4
760
11th to 20thNight
8%15%28%29%17%3
760
21st to endNight
9%21%28%26%13%2
836
Page generated at 2024-02-12 04:35:33. Version ac07

Copyright 2024 Attilla Danko


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