Seagrape Drive
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Seagrape Drive clear sky chart from 2005-11-05 to 2017-09-20.

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
68%
16144
19%
47005
17%
16101
71%
16101
31%
29507

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
57%
719
20%
2327
17%
716
62%
716
28%
1414
January16th to endNight
58%
768
26%
2406
22%
768
64%
768
35%
1363
February1st to 15thNight
56%
702
26%
2104
21%
698
62%
698
36%
1216
February16th to endNight
65%
631
31%
1777
23%
631
72%
631
42%
997
March1st to 15thNight
64%
720
28%
1980
21%
720
70%
720
46%
1069
March16th to endNight
68%
768
29%
2112
23%
768
72%
768
44%
1155
April1st to 15thNight
73%
718
25%
1976
21%
718
76%
718
48%
1053
April16th to endNight
68%
720
26%
1854
18%
720
71%
720
44%
1075
May1st to 15thNight
82%
692
25%
1772
18%
692
83%
692
53%
960
May16th to endNight
76%
561
17%
1683
16%
561
77%
561
32%
1046
June1st to 15thNight
62%
540
6%
1620
4%
540
62%
540
17%
1226
June16th to endNight
75%
540
7%
1620
6%
540
75%
540
21%
1185
July1st to 15thNight
75%
510
5%
1530
6%
510
75%
510
19%
1146
July16th to endNight
82%
564
7%
1595
7%
531
83%
531
25%
1106
August1st to 15thNight
77%
558
5%
1653
6%
555
77%
555
23%
1176
August16th to endNight
68%
764
5%
2101
4%
764
68%
764
17%
1598
September1st to 15thNight
70%
720
4%
1980
4%
720
71%
720
19%
1481
September16th to endNight
62%
677
5%
1870
6%
677
62%
677
13%
1494
October1st to 15thNight
69%
660
19%
1878
19%
660
70%
660
28%
1234
October16th to endNight
61%
704
21%
2112
22%
704
63%
704
28%
1357
November1st to 15thNight
68%
700
29%
2101
28%
700
73%
700
39%
1194
November16th to endNight
63%
720
28%
2160
24%
720
68%
720
32%
1293
December1st to 15thNight
66%
720
24%
2298
23%
720
70%
720
33%
1318
December16th to endNight
70%
768
25%
2496
26%
768
73%
768
37%
1351

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
8%5%36%7%47%6%7%9%35%
47812
Night
6%4245%35%5%7%10%44%
47212
TransparencyDay
40%11%16%16%11%3
47513
Night
32%10%18%20%13%3
47015
SeeingDay
8%110%22%28%28%
5966
Night
7%112%32%32%13%
16150

By Month

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
6%6%26%6%346%6%11%39%
1611
16th to endDay
7%435%435%5%5%8%46%
1815
February1st to 15thDay
10%434335%349%47%
1750
16th to endDay
5%2243145%6%8%54%
1694
March1st to 15thDay
43245%345%6%9%49%
1980
16th to endDay
5%3245%345%6%8%49%
2111
April1st to 15thDay
5%2235%36%5%6%11%47%
1972
16th to endDay
6%425%5%45%5%5%9%44%
2103
May1st to 15thDay
4323425%6%6%8%52%
2187
16th to endDay
8%5%36%7%47%6%7%9%32%
2431
June1st to 15thDay
13%8%48%9%5%7%7%8%10%16%
2340
16th to endDay
9%6%38%8%5%9%7%9%9%20%
2340
July1st to 15thDay
9%7%38%9%6%10%8%8%10%17%
2340
16th to endDay
7%5%37%8%6%12%9%8%11%19%
2465
August1st to 15thDay
7%427%10%6%9%9%9%11%20%
2277
16th to endDay
9%6%310%8%5%8%7%9%8%21%
2101
September1st to 15thDay
8%7%49%9%5%9%7%8%9%19%
1980
16th to endDay
13%8%410%9%47%7%7%7%17%
1859
October1st to 15thDay
8%5%27%8%47%7%6%9%32%
1752
16th to endDay
11%5%16%6%45%6%7%8%36%
1760
November1st to 15thDay
5%4246%45%6%6%8%46%
1757
16th to endDay
9%425%435%6%5%7%45%
1800
December1st to 15thDay
9%435%5%345%5%9%41%
1659
16th to endDay
6%424435%6%7%10%45%
1728
January1st to 15thNight
8%425%5%35%5%6%10%41%
2327
16th to endNight
6%42443446%9%48%
2406
February1st to 15thNight
9%42342435%8%50%
2103
16th to endNight
421442446%8%56%
1777
March1st to 15thNight
421333445%8%57%
1980
16th to endNight
431332346%9%56%
2112
April1st to 15thNight
321232335%9%61%
1976
16th to endNight
6%31333445%11%54%
1854
May1st to 15thNight
22242345%11%61%
1772
16th to endNight
6%5%25%425%6%7%12%40%
1682
June1st to 15thNight
12%7%37%6%46%7%7%11%25%
1620
16th to endNight
5%5%26%7%36%7%10%12%32%
1620
July1st to 15thNight
6%5%35%6%46%6%9%13%32%
1620
16th to endNight
32246%47%9%12%12%34%
1703
August1st to 15thNight
5%425%6%46%7%10%14%32%
1664
16th to endNight
6%427%8%47%8%7%12%29%
2101
September1st to 15thNight
6%426%7%46%8%9%13%29%
1980
16th to endNight
10%6%28%8%48%8%7%9%25%
1870
October1st to 15thNight
6%5%25%6%35%6%8%10%39%
1878
16th to endNight
10%5%25%5%35%5%5%8%41%
2112
November1st to 15thNight
7%32343345%8%53%
2101
16th to endNight
8%5%24435%45%7%48%
2160
December1st to 15thNight
6%4243246%5%10%47%
2298
16th to endNight
431342446%9%53%
2496

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
36%8%15%20%11%5%
1612
16th to endDay
33%6%12%24%17%5%
1815
February1st to 15thDay
34%5%10%22%17%9%
1752
16th to endDay
23%8%15%24%20%7%
1694
March1st to 15thDay
26%8%14%25%20%5%
1980
16th to endDay
30%6%14%22%17%8%
2112
April1st to 15thDay
27%8%19%24%15%3
1972
16th to endDay
32%7%15%21%19%4
2103
May1st to 15thDay
25%8%17%26%17%5%
2187
16th to endDay
43%10%18%19%8%
2435
June1st to 15thDay
57%13%16%10%2
2340
16th to endDay
53%17%19%9%1
2340
July1st to 15thDay
54%21%19%5%
2201
16th to endDay
51%18%22%7%
2310
August1st to 15thDay
48%18%22%10%
2264
16th to endDay
53%18%20%7%
2101
September1st to 15thDay
54%18%20%6%
1980
16th to endDay
60%16%12%8%2
1859
October1st to 15thDay
42%13%15%14%12%2
1752
16th to endDay
40%8%11%16%15%7%
1760
November1st to 15thDay
31%7%12%19%20%8%
1757
16th to endDay
33%8%11%16%19%10%
1800
December1st to 15thDay
38%7%13%18%17%4
1659
16th to endDay
29%7%15%22%18%4
1728
January1st to 15thNight
35%7%15%24%14%3
2327
16th to endNight
30%6%14%26%17%6%
2406
February1st to 15thNight
31%49%24%20%9%
2112
16th to endNight
24%7%13%24%21%8%
1777
March1st to 15thNight
24%414%30%20%5%
1980
16th to endNight
23%6%14%28%21%5%
2112
April1st to 15thNight
20%6%17%31%18%5%
1976
16th to endNight
24%8%14%24%24%4
1854
May1st to 15thNight
17%7%18%32%18%4
1773
16th to endNight
32%9%21%24%12%
1684
June1st to 15thNight
49%13%24%10%2
1620
16th to endNight
39%18%28%11%2
1620
July1st to 15thNight
39%20%29%9%1
1530
16th to endNight
33%18%34%13%
1595
August1st to 15thNight
36%17%30%15%
1653
16th to endNight
43%19%26%9%
2101
September1st to 15thNight
39%20%28%10%1
1980
16th to endNight
49%19%17%11%2
1870
October1st to 15thNight
35%11%19%17%14%2
1878
16th to endNight
39%6%12%17%17%5%
2112
November1st to 15thNight
28%6%11%23%22%7%
2101
16th to endNight
33%6%10%19%20%9%
2160
December1st to 15thNight
30%7%16%22%19%4
2298
16th to endNight
26%7%15%25%21%3
2496

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%324%32%17%1
90
16th to endDay
15%11%25%32%13%2
96
February1st to 15thDay
5%423%36%24%5%
90
16th to endDay
4224%44%24%
195
March1st to 15thDay
4218%44%27%2
270
16th to endDay
5%220%36%27%7%
288
April1st to 15thDay
5%20%32%31%8%
270
16th to endDay
7%15%34%35%7%
270
May1st to 15thDay
310%25%40%19%
288
16th to endDay
6%1420%34%32%
331
June1st to 15thDay
18%16%10%29%33%
315
16th to endDay
7%19%24%56%
315
July1st to 15thDay
6%15%21%64%
305
16th to endDay
8%10%22%57%
326
August1st to 15thDay
417%30%56%
313
16th to endDay
10%5%8%24%50%
332
September1st to 15thDay
8%149%25%50%
315
16th to endDay
10%28%32%44%
270
October1st to 15thDay
5%9%27%39%17%
255
16th to endDay
12%16%30%27%12%
272
November1st to 15thDay
6%112%32%35%12%
265
16th to endDay
5%119%41%27%4
270
December1st to 15thDay
15%318%34%22%4
129
16th to endDay
313%34%43%5%
96
January1st to 15thNight
9%417%40%26%1
720
16th to endNight
7%223%45%19%
768
February1st to 15thNight
10%224%43%19%
704
16th to endNight
5%220%49%22%
631
March1st to 15thNight
5%222%45%22%1
720
16th to endNight
6%117%47%25%1
768
April1st to 15thNight
3214%49%28%1
718
16th to endNight
7%16%44%29%
720
May1st to 15thNight
38%48%35%4
693
16th to endNight
6%15%30%45%10%
563
June1st to 15thNight
12%5%18%44%19%
540
16th to endNight
428%44%39%
540
July1st to 15thNight
6%17%37%46%
510
16th to endNight
315%36%53%
564
August1st to 15thNight
7%16%43%41%
558
16th to endNight
7%311%39%37%
764
September1st to 15thNight
7%49%38%39%
720
16th to endNight
12%1315%41%25%
677
October1st to 15thNight
8%6%32%39%12%
660
16th to endNight
13%113%31%31%8%
704
November1st to 15thNight
8%15%40%31%4
700
16th to endNight
10%116%41%27%1
720
December1st to 15thNight
7%115%44%29%2
720
16th to endNight
5%115%39%34%3
768
Page generated at 2017-09-21 07:18:23. Version ac04

Copyright 2017 A. Danko


Seagrape Drive Clear Sky Chart | Charts Home