Fanthorp Inn State Historic Site
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Fanthorp Inn State Historic Site clear sky chart from 2005-11-05 to 2019-06-10.

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
49%
17725
24%
53878
17%
17676
56%
17676
31%
32045

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
34%
1050
26%
2717
11%
1045
43%
1045
29%
1775
January16th to endNight
31%
1120
26%
2912
9%
1120
41%
1120
30%
1888
February1st to 15thNight
27%
886
22%
2527
8%
880
37%
880
23%
1669
February16th to endNight
21%
647
24%
2117
8%
647
35%
647
21%
1344
March1st to 15thNight
26%
630
25%
2310
13%
630
41%
630
20%
1432
March16th to endNight
33%
672
22%
2464
14%
672
45%
672
26%
1419
April1st to 15thNight
34%
629
23%
2290
14%
629
47%
629
25%
1323
April16th to endNight
35%
624
23%
2078
16%
624
48%
624
29%
1211
May1st to 15thNight
36%
629
21%
1925
16%
629
44%
629
28%
1188
May16th to endNight
54%
659
25%
1973
21%
657
64%
657
40%
1101
June1st to 15thNight
76%
612
23%
1836
26%
612
79%
612
49%
923
June16th to endNight
76%
585
20%
1755
23%
585
78%
585
38%
1008
July1st to 15thNight
80%
555
20%
1665
23%
555
82%
555
41%
913
July16th to endNight
83%
612
20%
1738
24%
579
84%
579
42%
947
August1st to 15thNight
89%
575
29%
1717
33%
572
90%
572
57%
803
August16th to endNight
78%
621
17%
2096
20%
621
79%
621
30%
1234
September1st to 15thNight
74%
585
16%
2145
19%
585
75%
585
27%
1266
September16th to endNight
70%
582
26%
2145
29%
582
71%
582
29%
1212
October1st to 15thNight
71%
692
33%
2252
29%
692
74%
692
42%
1128
October16th to endNight
55%
832
34%
2496
22%
832
63%
832
42%
1340
November1st to 15thNight
48%
820
27%
2460
19%
820
54%
820
32%
1468
November16th to endNight
46%
938
30%
2618
16%
938
54%
938
35%
1563
December1st to 15thNight
36%
1050
26%
2730
12%
1050
44%
1050
27%
1846
December16th to endNight
33%
1120
20%
2912
9%
1120
39%
1120
24%
2044

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
11%5%25%5%35%5%5%7%41%
54619
Night
10%5%2442345%8%49%
54081
TransparencyDay
40%7%11%18%16%6%
54319
Night
33%6%12%20%17%9%
53886
SeeingDay
12%6%19%26%26%9%
7622
Night
13%6%25%33%18%2
17726

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
17%5%34433345%44%
1881
16th to endDay
18%6%24323245%45%
2016
February1st to 15thDay
19%7%35%313435%41%
2000
16th to endDay
20%7%35%5%23335%39%
1927
March1st to 15thDay
20%8%25%5%23346%37%
2310
16th to endDay
13%6%35%42435%6%44%
2462
April1st to 15thDay
12%7%36%5%34446%42%
2318
16th to endDay
10%6%25%5%3435%6%43%
2487
May1st to 15thDay
10%6%37%5%345%6%8%36%
2682
16th to endDay
7%425%6%46%6%6%8%40%
2846
June1st to 15thDay
5%2246%46%5%7%9%45%
2653
16th to endDay
7%426%7%5%8%7%7%9%33%
2535
July1st to 15thDay
8%325%6%46%7%8%10%35%
2535
16th to endDay
5%325%7%38%7%8%11%35%
2674
August1st to 15thDay
32136%46%5%7%11%48%
2486
16th to endDay
6%425%7%47%7%7%9%36%
2451
September1st to 15thDay
9%5%26%6%46%6%6%7%38%
2145
16th to endDay
7%436%7%45%7%6%6%40%
2145
October1st to 15thDay
8%4136%345%45%52%
2023
16th to endDay
12%41321333459%
2080
November1st to 15thDay
9%6%35%5%25%45%7%44%
2058
16th to endDay
13%5%24423445%50%
1999
December1st to 15thDay
19%8%34423245%40%
1890
16th to endDay
19%8%36%6%23436%35%
2016
January1st to 15thNight
15%7%14324335%47%
2717
16th to endNight
17%424313346%47%
2912
February1st to 15thNight
16%8%26%423235%43%
2524
16th to endNight
16%6%34433445%44%
2117
March1st to 15thNight
16%7%25%423346%42%
2310
16th to endNight
10%5%24423447%48%
2464
April1st to 15thNight
9%5%2442445%8%46%
2290
16th to endNight
10%5%25%324348%48%
2078
May1st to 15thNight
9%5%25%5%2446%8%44%
1925
16th to endNight
42233336%6%9%53%
1971
June1st to 15thNight
221322347%11%58%
1836
16th to endNight
3213425%6%7%11%51%
1755
July1st to 15thNight
332332446%12%53%
1755
16th to endNight
2112425%5%7%13%51%
1846
August1st to 15thNight
21221236%13%63%
1727
16th to endNight
4315%436%5%7%12%46%
2096
September1st to 15thNight
6%5%35%4345%6%11%44%
2145
16th to endNight
7%4145%345%5%9%48%
2145
October1st to 15thNight
5%223323347%61%
2252
16th to endNight
10%31322222463%
2496
November1st to 15thNight
10%41443345%6%51%
2460
16th to endNight
11%414322445%53%
2618
December1st to 15thNight
16%7%24423346%43%
2730
16th to endNight
18%8%25%423336%40%
2912

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
41%37%14%22%9%
1882
16th to endDay
41%26%14%22%12%
2016
February1st to 15thDay
45%5%5%15%17%10%
2001
16th to endDay
48%36%13%16%9%
1927
March1st to 15thDay
48%5%7%12%20%6%
2310
16th to endDay
40%5%8%18%21%5%
2464
April1st to 15thDay
43%5%6%17%16%9%
2318
16th to endDay
39%6%10%16%19%6%
2487
May1st to 15thDay
44%7%11%17%13%6%
2682
16th to endDay
38%9%12%21%16%1
2850
June1st to 15thDay
31%9%16%24%16%1
2653
16th to endDay
43%10%14%19%10%1
2535
July1st to 15thDay
38%10%19%20%9%
2396
16th to endDay
36%13%17%23%8%
2519
August1st to 15thDay
27%10%19%28%12%1
2472
16th to endDay
40%11%18%19%7%1
2451
September1st to 15thDay
41%10%13%18%11%4
2145
16th to endDay
40%9%11%17%14%7%
2145
October1st to 15thDay
32%6%11%19%15%13%
2023
16th to endDay
29%35%13%29%18%
2080
November1st to 15thDay
37%6%10%18%17%8%
2058
16th to endDay
36%46%14%23%14%
1999
December1st to 15thDay
46%47%16%16%8%
1890
16th to endDay
50%37%14%15%7%
2016
January1st to 15thNight
39%36%17%19%13%
2717
16th to endNight
38%45%14%22%14%
2912
February1st to 15thNight
44%35%13%18%14%
2534
16th to endNight
42%5%7%15%15%13%
2117
March1st to 15thNight
42%5%7%15%19%9%
2310
16th to endNight
35%5%11%18%20%7%
2464
April1st to 15thNight
34%6%10%18%17%11%
2290
16th to endNight
34%6%10%20%19%9%
2078
May1st to 15thNight
37%6%13%19%16%7%
1926
16th to endNight
24%8%16%30%17%2
1973
June1st to 15thNight
18%6%18%31%22%1
1836
16th to endNight
25%9%19%30%13%1
1755
July1st to 15thNight
22%9%25%30%11%
1665
16th to endNight
20%10%28%30%9%
1738
August1st to 15thNight
12%6%26%38%13%1
1717
16th to endNight
28%12%24%25%7%1
2096
September1st to 15thNight
32%9%21%19%10%5%
2145
16th to endNight
31%8%14%19%17%8%
2145
October1st to 15thNight
23%5%12%26%18%14%
2252
16th to endNight
27%35%14%28%21%
2496
November1st to 15thNight
33%6%11%21%18%8%
2460
16th to endNight
32%47%16%23%16%
2618
December1st to 15thNight
42%48%17%17%8%
2730
16th to endNight
46%46%14%17%10%
2912

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%10%32%25%7%2
180
16th to endDay
22%16%36%15%7%1
192
February1st to 15thDay
27%16%31%20%4
180
16th to endDay
32%19%30%15%1
159
March1st to 15thDay
22%23%37%11%5%
180
16th to endDay
9%10%43%25%9%
192
April1st to 15thDay
11%20%35%21%9%1
197
16th to endDay
16%11%31%26%12%1
379
May1st to 15thDay
12%9%35%29%11%1
579
16th to endDay
8%6%28%34%18%3
677
June1st to 15thDay
4113%37%35%7%
616
16th to endDay
9%110%32%34%11%
570
July1st to 15thDay
6%6%28%38%19%
550
16th to endDay
3325%47%20%
595
August1st to 15thDay
5%222%53%15%
549
16th to endDay
10%5%13%45%25%
363
September1st to 15thDay
11%6%16%41%23%
180
16th to endDay
7%427%33%26%
180
October1st to 15thDay
4110%33%31%17%
180
16th to endDay
22%5%22%20%21%6%
192
November1st to 15thDay
19%7%23%33%15%1
180
16th to endDay
16%12%26%31%9%5%
180
December1st to 15thDay
31%7%25%22%6%7%
180
16th to endDay
28%18%32%15%4
192
January1st to 15thNight
19%11%29%29%9%
1050
16th to endNight
19%12%33%27%6%
1120
February1st to 15thNight
20%12%34%26%5%
886
16th to endNight
21%11%41%22%2
647
March1st to 15thNight
19%11%39%24%5%
630
16th to endNight
12%8%43%27%7%
672
April1st to 15thNight
10%12%40%31%5%
629
16th to endNight
14%6%40%28%10%
624
May1st to 15thNight
11%9%39%31%7%
630
16th to endNight
5%232%39%18%1
659
June1st to 15thNight
314%52%26%1
612
16th to endNight
311%51%28%4
585
July1st to 15thNight
37%47%35%6%
555
16th to endNight
2348%39%4
612
August1st to 15thNight
3248%41%3
575
16th to endNight
5%5%38%43%5%
621
September1st to 15thNight
7%16%32%44%7%
585
16th to endNight
12%8%29%40%8%
582
October1st to 15thNight
6%214%39%31%5%
692
16th to endNight
12%325%32%23%2
832
November1st to 15thNight
12%5%30%33%17%
820
16th to endNight
14%7%28%31%16%
938
December1st to 15thNight
21%9%28%28%10%
1050
16th to endNight
23%10%29%27%7%
1120
Page generated at 2019-06-10 18:29:50. Version ac04

Copyright 2019 A. Danko


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