Bertucci's Sky
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bertucci's Sky clear sky chart from 2005-11-05 to 2017-09-22.

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
59%
15229
28%
46920
22%
15200
66%
15200
42%
23771

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
55%
716
21%
2506
18%
716
63%
716
31%
1342
January16th to endNight
52%
768
23%
2523
21%
768
58%
768
31%
1402
February1st to 15thNight
51%
698
23%
2219
21%
697
58%
697
31%
1232
February16th to endNight
49%
632
26%
1895
21%
632
58%
632
33%
1073
March1st to 15thNight
48%
720
20%
2124
14%
720
56%
720
34%
1186
March16th to endNight
44%
768
20%
2015
12%
768
51%
768
35%
1183
April1st to 15thNight
47%
719
21%
1799
9%
719
53%
719
35%
1100
April16th to endNight
53%
720
22%
1800
10%
720
57%
720
42%
1024
May1st to 15thNight
57%
572
26%
1652
18%
572
62%
572
47%
829
May16th to endNight
62%
374
23%
1496
25%
374
66%
374
36%
696
June1st to 15thNight
66%
360
26%
1440
29%
360
74%
360
43%
622
June16th to endNight
71%
360
34%
1440
40%
360
81%
360
65%
479
July1st to 15thNight
84%
340
33%
1360
42%
340
88%
340
65%
466
July16th to endNight
80%
418
37%
1455
39%
393
84%
393
59%
551
August1st to 15thNight
77%
625
34%
1698
22%
622
81%
622
63%
806
August16th to endNight
76%
764
42%
1910
24%
764
80%
764
75%
887
September1st to 15thNight
81%
720
41%
1800
26%
720
85%
720
77%
826
September16th to endNight
70%
683
41%
1853
31%
683
77%
683
63%
855
October1st to 15thNight
63%
660
31%
1952
26%
660
72%
660
48%
969
October16th to endNight
67%
704
36%
2139
33%
704
76%
704
54%
964
November1st to 15thNight
63%
700
29%
2275
29%
700
69%
700
42%
1144
November16th to endNight
52%
720
29%
2361
23%
720
63%
720
40%
1142
December1st to 15thNight
48%
720
19%
2520
15%
720
55%
720
28%
1403
December16th to endNight
43%
768
22%
2688
18%
768
52%
768
23%
1590

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
121232345%7%63%
47972
Night
121221345%8%65%
47098
TransparencyDay
20%7%11%20%23%16%
47647
Night
18%8%13%23%23%12%
46922
SeeingDay
9%23%33%22%9%2
5791
Night
410%22%31%23%6%
15241

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 15thDay
12123246%7%10%56%
1432
16th to endDay
2413426%6%8%11%48%
1698
February1st to 15thDay
4133345%7%11%54%
1643
16th to endDay
3244245%6%11%53%
1579
March1st to 15thDay
214335%6%8%12%50%
1833
16th to endDay
3134246%7%10%55%
2208
April1st to 15thDay
24145%35%5%6%10%51%
2149
16th to endDay
232231335%8%62%
2160
May1st to 15thDay
2313423447%62%
2296
16th to endDay
4413425%5%5%7%54%
2615
June1st to 15thDay
332314346%65%
2520
16th to endDay
111121223478%
2520
July1st to 15thDay
111231343473%
2520
16th to endDay
111221233474%
2612
August1st to 15thDay
111231234474%
2253
16th to endDay
11111222480%
2292
September1st to 15thDay
112212245%76%
2160
16th to endDay
11221323476%
1918
October1st to 15thDay
3212313346%65%
1675
16th to endDay
12331235%6%68%
1733
November1st to 15thDay
131331346%9%60%
1584
16th to endDay
121222446%9%62%
1596
December1st to 15thDay
1322325%5%7%10%54%
1440
16th to endDay
2245%35%5%8%12%47%
1536
January1st to 15thNight
131432447%11%54%
2506
16th to endNight
13234245%6%11%52%
2523
February1st to 15thNight
12233245%7%9%57%
2209
16th to endNight
3234235%6%10%56%
1895
March1st to 15thNight
3122135%7%11%58%
2124
16th to endNight
2222245%6%10%60%
2015
April1st to 15thNight
12134245%7%10%55%
1799
16th to endNight
22221335%8%65%
1800
May1st to 15thNight
2112312348%68%
1652
16th to endNight
331341235%6%64%
1496
June1st to 15thNight
311221244470%
1440
16th to endNight
1111122384%
1440
July1st to 15thNight
11111223480%
1440
16th to endNight
111111322477%
1554
August1st to 15thNight
11121233476%
1707
16th to endNight
1111112483%
1910
September1st to 15thNight
111112483%
1800
16th to endNight
1122222478%
1853
October1st to 15thNight
3212313435%69%
1952
16th to endNight
1212112337%72%
2139
November1st to 15thNight
12221345%9%65%
2275
16th to endNight
12221335%10%65%
2361
December1st to 15thNight
1214325%5%7%11%55%
2520
16th to endNight
3244246%7%13%50%
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
22%12%18%26%16%3
1432
16th to endDay
30%10%14%20%16%8%
1698
February1st to 15thDay
24%12%16%25%16%4
1643
16th to endDay
27%12%13%28%15%2
1579
March1st to 15thDay
27%13%18%19%17%3
1833
16th to endDay
24%12%21%23%13%3
2208
April1st to 15thDay
29%9%17%22%17%3
2149
16th to endDay
22%9%17%26%20%4
2160
May1st to 15thDay
24%5%10%30%24%4
2296
16th to endDay
29%6%11%24%21%5%
2619
June1st to 15thDay
20%6%10%20%27%13%
2520
16th to endDay
11%2415%36%29%
2520
July1st to 15thDay
12%3410%23%45%
2371
16th to endDay
14%2412%20%45%
2448
August1st to 15thDay
13%3411%23%43%
2237
16th to endDay
10%2310%35%37%
2292
September1st to 15thDay
13%3413%34%31%
2160
16th to endDay
13%26%24%33%19%
1918
October1st to 15thDay
20%5%7%24%28%12%
1675
16th to endDay
17%6%11%26%28%9%
1733
November1st to 15thDay
21%9%15%25%20%7%
1584
16th to endDay
18%9%16%25%25%4
1596
December1st to 15thDay
25%13%16%26%15%1
1440
16th to endDay
29%13%15%18%19%2
1536
January1st to 15thNight
24%10%16%26%19%2
2506
16th to endNight
25%10%16%20%17%8%
2523
February1st to 15thNight
23%11%15%29%13%6%
2220
16th to endNight
22%12%16%29%14%3
1895
March1st to 15thNight
19%13%19%24%18%5%
2124
16th to endNight
19%14%22%24%15%3
2015
April1st to 15thNight
24%10%19%26%16%1
1799
16th to endNight
17%10%20%28%18%3
1800
May1st to 15thNight
17%6%13%30%26%5%
1653
16th to endNight
21%6%16%27%22%4
1496
June1st to 15thNight
16%6%10%22%27%14%
1440
16th to endNight
8%25%18%35%29%
1440
July1st to 15thNight
9%2410%28%45%
1360
16th to endNight
12%2410%23%46%
1455
August1st to 15thNight
13%3414%25%39%
1698
16th to endNight
8%2313%38%34%
1910
September1st to 15thNight
7%15%14%38%30%
1800
16th to endNight
12%27%24%33%20%
1853
October1st to 15thNight
18%5%8%30%29%8%
1952
16th to endNight
13%413%27%34%6%
2139
November1st to 15thNight
17%10%13%29%21%8%
2275
16th to endNight
16%8%14%29%25%5%
2361
December1st to 15thNight
23%14%19%23%15%3
2520
16th to endNight
27%14%16%19%17%3
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
21%18%45%8%6%
60
16th to endDay
12%23%25%23%12%2
226
February1st to 15thDay
13%21%29%22%12%
248
16th to endDay
11%29%32%19%6%
238
March1st to 15thDay
13%35%25%13%11%1
270
16th to endDay
14%35%28%15%6%
288
April1st to 15thDay
14%34%26%16%6%
269
16th to endDay
11%35%29%17%5%
270
May1st to 15thDay
12%31%27%20%5%2
288
16th to endDay
12%25%26%23%8%3
330
June1st to 15thDay
11%28%32%19%6%1
315
16th to endDay
416%44%23%6%4
315
July1st to 15thDay
313%38%28%13%1
305
16th to endDay
215%43%23%10%4
327
August1st to 15thDay
419%39%23%10%3
315
16th to endDay
213%40%25%11%6%
332
September1st to 15thDay
310%42%29%12%2
315
16th to endDay
6%17%34%30%8%2
280
October1st to 15thDay
10%21%31%21%12%2
255
16th to endDay
8%21%30%28%10%
245
November1st to 15thDay
6%14%20%13%38%6%
90
16th to endDay
9%29%29%19%10%2
86
December1st to 15thDay
20%35%28%11%31
60
16th to endDay
10%17%21%26%20%3
64
January1st to 15thNight
412%23%28%20%10%
720
16th to endNight
5%9%27%30%17%9%
768
February1st to 15thNight
413%26%28%21%5%
704
16th to endNight
5%18%23%30%16%5%
632
March1st to 15thNight
418%26%26%18%5%
720
16th to endNight
422%28%25%17%2
768
April1st to 15thNight
6%15%26%29%19%1
719
16th to endNight
6%15%23%28%18%7%
720
May1st to 15thNight
412%22%34%21%5%
573
16th to endNight
5%5%22%32%31%2
375
June1st to 15thNight
45%20%41%25%3
360
16th to endNight
223%40%30%2
360
July1st to 15thNight
210%49%35%1
340
16th to endNight
2111%38%39%5%
418
August1st to 15thNight
2114%40%35%4
625
16th to endNight
1315%40%32%5%
764
September1st to 15thNight
1213%34%40%8%
720
16th to endNight
38%16%28%32%9%
683
October1st to 15thNight
5%7%19%32%24%9%
660
16th to endNight
49%16%30%25%14%
704
November1st to 15thNight
39%22%32%23%8%
700
16th to endNight
5%15%24%25%20%7%
720
December1st to 15thNight
415%26%30%15%7%
720
16th to endNight
5%16%31%27%13%5%
768
Page generated at 2017-09-23 03:43:45. Version ac04

Copyright 2017 A. Danko


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