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Harrington Beach State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Harrington Beach State Park clear sky chart from 2005-11-05 to 2019-09-17.

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
41%
18740
17%
54728
10%
18698
47%
18698
23%
37332

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
20%
1050
13%
2926
3%
1045
29%
1045
15%
2256
January16th to endNight
21%
1120
12%
3136
4%
1120
29%
1120
15%
2416
February1st to 15thNight
24%
953
14%
2621
3%
953
32%
953
17%
1919
February16th to endNight
27%
735
16%
2205
6%
735
35%
735
17%
1601
March1st to 15thNight
35%
840
16%
2520
9%
840
41%
840
20%
1732
March16th to endNight
42%
742
18%
2352
14%
742
49%
742
22%
1578
April1st to 15thNight
34%
629
15%
2097
11%
629
43%
629
19%
1457
April16th to endNight
47%
624
19%
1963
16%
624
52%
624
25%
1286
May1st to 15thNight
48%
630
16%
1824
12%
630
51%
630
22%
1276
May16th to endNight
57%
658
16%
1754
12%
657
59%
657
31%
1146
June1st to 15thNight
62%
630
16%
1680
11%
630
64%
630
34%
1071
June16th to endNight
61%
630
15%
1680
10%
630
64%
630
32%
1088
July1st to 15thNight
74%
600
18%
1600
14%
600
75%
600
44%
928
July16th to endNight
74%
660
18%
1673
14%
627
74%
627
42%
985
August1st to 15thNight
73%
620
22%
1723
18%
617
74%
617
40%
992
August16th to endNight
66%
669
20%
2230
20%
669
69%
669
33%
1269
September1st to 15thNight
62%
639
26%
2109
26%
639
66%
639
32%
1214
September16th to endNight
58%
782
25%
2159
18%
782
62%
782
35%
1321
October1st to 15thNight
46%
780
20%
2242
14%
780
51%
780
27%
1475
October16th to endNight
34%
832
16%
2675
10%
832
43%
832
21%
1784
November1st to 15thNight
36%
820
21%
2666
15%
820
44%
820
21%
1742
November16th to endNight
26%
927
15%
2817
7%
927
35%
927
17%
2026
December1st to 15thNight
21%
1050
11%
2940
4%
1050
28%
1050
13%
2272
December16th to endNight
17%
1120
11%
3136
2%
1120
25%
1120
11%
2498

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
12%7%36%5%35%5%5%7%38%
55965
Night
14%7%35%5%2445%6%38%
54896
Cloud CoverDay
12%7%36%5%35%5%6%7%37%
55974
Night
14%8%35%5%3445%6%37%
54901
TransparencyDay
43%6%13%23%11%1
55651
Night
45%6%11%22%12%1
54728
SeeingDay
15%318%33%23%5%
8787
Night
18%6%24%30%16%3
18744

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
14%10%5%6%5%35%46%9%27%
1672
16th to endDay
12%12%5%9%7%445%6%7%23%
1792
February1st to 15thDay
14%11%5%8%5%2445%6%30%
1900
16th to endDay
12%10%48%5%25%5%5%6%31%
1840
March1st to 15thDay
12%8%46%5%36%5%47%34%
2090
16th to endDay
14%8%36%5%35%5%5%6%35%
2586
April1st to 15thDay
18%9%46%5%25%45%6%30%
2511
16th to endDay
17%7%35%5%34446%36%
2601
May1st to 15thDay
17%7%36%435%45%7%33%
2783
16th to endDay
11%5%25%425%5%6%8%41%
3065
June1st to 15thDay
11%5%25%5%35%5%5%8%40%
2940
16th to endDay
8%425%5%335%6%10%44%
2940
July1st to 15thDay
43135%345%6%9%50%
2940
16th to endDay
6%3244345%7%8%48%
3103
August1st to 15thDay
6%224436%46%9%47%
2806
16th to endDay
11%425%5%2445%7%46%
2676
September1st to 15thDay
11%424434447%46%
2496
16th to endDay
8%5%25%5%25%46%9%43%
2156
October1st to 15thDay
18%5%35%42445%6%39%
2044
16th to endDay
16%5%36%6%445%5%6%34%
1901
November1st to 15thDay
13%8%37%5%35%46%7%36%
1852
16th to endDay
15%9%36%5%4445%8%33%
1799
December1st to 15thDay
17%10%35%5%36%6%5%8%25%
1680
16th to endDay
18%13%5%8%5%35%5%6%6%20%
1792
January1st to 15thNight
15%13%5%7%6%2346%5%29%
2926
16th to endNight
13%10%49%6%345%7%7%26%
3136
February1st to 15thNight
15%12%45%5%2445%5%34%
2619
16th to endNight
15%11%37%5%35%44433%
2205
March1st to 15thNight
14%7%45%5%25%5%5%6%37%
2507
16th to endNight
14%7%35%435%5%46%38%
2352
April1st to 15thNight
20%10%34424445%35%
2097
16th to endNight
18%6%35%42335%5%41%
1963
May1st to 15thNight
19%6%26%5%25%45%7%32%
1824
16th to endNight
11%5%25%5%15%5%5%10%40%
1752
June1st to 15thNight
13%425%3245%6%8%44%
1680
16th to endNight
11%425%5%345%6%7%43%
1680
July1st to 15thNight
5%3234245%5%9%54%
1680
16th to endNight
6%2235%25%47%8%52%
1769
August1st to 15thNight
5%2244345%6%8%51%
1732
16th to endNight
9%32443445%6%50%
2230
September1st to 15thNight
9%324424446%52%
2109
16th to endNight
11%41443445%7%49%
2159
October1st to 15thNight
17%6%2442345%6%42%
2242
16th to endNight
17%7%245%2445%7%38%
2675
November1st to 15thNight
14%8%25%425%446%41%
2666
16th to endNight
16%9%36%5%3445%6%33%
2817
December1st to 15thNight
19%11%46%5%3445%7%26%
2940
16th to endNight
19%13%48%5%25%446%24%
3136

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
13%12%5%6%6%35%5%7%8%25%
1672
16th to endDay
13%12%6%9%7%446%6%7%21%
1792
February1st to 15thDay
14%11%6%8%5%245%5%6%30%
1900
16th to endDay
13%10%48%5%35%5%5%6%31%
1840
March1st to 15thDay
13%8%47%6%3445%7%33%
2100
16th to endDay
14%7%45%6%345%5%7%34%
2585
April1st to 15thDay
18%9%46%5%25%5%5%6%30%
2511
16th to endDay
17%7%26%5%34446%36%
2601
May1st to 15thDay
17%7%35%435%46%7%33%
2783
16th to endDay
11%5%245%3446%8%41%
3065
June1st to 15thDay
11%5%25%5%35%5%6%8%39%
2940
16th to endDay
7%5%25%5%345%6%10%44%
2940
July1st to 15thDay
43135%25%5%6%9%50%
2940
16th to endDay
6%4145%345%7%8%48%
3103
August1st to 15thDay
6%2245%36%46%9%47%
2806
16th to endDay
10%5%25%42445%7%46%
2676
September1st to 15thDay
11%425%43445%7%46%
2496
16th to endDay
8%5%16%6%245%6%9%43%
2156
October1st to 15thDay
17%6%35%42445%6%39%
2044
16th to endDay
15%7%26%6%345%6%7%34%
1901
November1st to 15thDay
12%8%47%5%25%45%7%36%
1852
16th to endDay
15%9%36%5%3445%8%32%
1799
December1st to 15thDay
18%10%36%5%46%47%8%23%
1680
16th to endDay
18%14%5%9%6%35%5%5%6%19%
1792
January1st to 15thNight
15%12%5%8%5%3347%5%28%
2926
16th to endNight
13%10%5%8%6%35%6%7%7%24%
3136
February1st to 15thNight
15%11%5%6%42445%5%33%
2612
16th to endNight
15%12%37%6%3445%432%
2205
March1st to 15thNight
14%7%46%6%35%45%6%36%
2520
16th to endNight
13%8%35%435%5%46%38%
2352
April1st to 15thNight
20%9%35%424445%35%
2097
16th to endNight
18%6%25%423446%40%
1963
May1st to 15thNight
19%6%36%435%46%7%32%
1823
16th to endNight
11%5%25%425%5%410%40%
1752
June1st to 15thNight
12%425%4245%5%8%44%
1680
16th to endNight
10%425%5%35%5%6%7%43%
1680
July1st to 15thNight
43244245%5%9%54%
1680
16th to endNight
5%3143245%7%9%51%
1769
August1st to 15thNight
5%3235%345%7%9%50%
1732
16th to endNight
9%32443435%6%50%
2230
September1st to 15thNight
10%314424446%51%
2109
16th to endNight
10%41442445%7%49%
2159
October1st to 15thNight
16%7%25%42345%6%42%
2242
16th to endNight
17%7%35%42345%6%38%
2675
November1st to 15thNight
14%8%34435%445%41%
2666
16th to endNight
16%9%35%5%35%45%6%32%
2817
December1st to 15thNight
18%12%36%6%25%46%7%24%
2940
16th to endNight
20%13%48%6%35%445%23%
3136

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
52%11%10%17%7%
1673
16th to endDay
58%10%10%15%5%
1792
February1st to 15thDay
54%6%10%20%7%1
1902
16th to endDay
52%5%11%19%8%1
1840
March1st to 15thDay
48%6%13%20%9%1
2100
16th to endDay
48%5%17%21%7%
2586
April1st to 15thDay
52%5%12%17%10%
2511
16th to endDay
47%412%17%13%3
2601
May1st to 15thDay
49%5%12%23%8%
2783
16th to endDay
39%6%13%25%13%1
3069
June1st to 15thDay
40%5%12%27%12%1
2940
16th to endDay
33%6%18%25%14%1
2940
July1st to 15thDay
28%6%15%32%14%3
2791
16th to endDay
30%6%17%26%15%3
2936
August1st to 15thDay
32%5%18%29%12%1
2791
16th to endDay
36%5%13%28%14%1
2676
September1st to 15thDay
36%6%11%27%15%1
2496
16th to endDay
36%6%15%29%12%
2156
October1st to 15thDay
45%412%24%12%
2044
16th to endDay
47%5%15%21%9%
1901
November1st to 15thDay
46%5%12%23%10%1
1852
16th to endDay
49%6%16%21%5%
1799
December1st to 15thDay
56%8%11%16%6%
1680
16th to endDay
63%6%11%12%6%
1792
January1st to 15thNight
54%9%8%16%10%
2926
16th to endNight
54%9%12%16%6%
3136
February1st to 15thNight
52%5%9%20%9%1
2621
16th to endNight
53%49%20%9%1
2205
March1st to 15thNight
47%5%12%20%12%1
2520
16th to endNight
46%5%11%25%10%1
2352
April1st to 15thNight
51%47%18%15%1
2097
16th to endNight
44%410%20%14%4
1963
May1st to 15thNight
48%5%12%22%11%
1824
16th to endNight
38%5%14%23%14%3
1754
June1st to 15thNight
36%5%11%29%16%1
1680
16th to endNight
37%6%13%23%17%1
1680
July1st to 15thNight
26%5%13%28%21%4
1600
16th to endNight
27%5%16%28%17%3
1673
August1st to 15thNight
28%6%17%29%16%2
1723
16th to endNight
32%5%12%28%18%2
2230
September1st to 15thNight
32%6%8%27%21%2
2109
16th to endNight
33%5%10%35%13%1
2159
October1st to 15thNight
41%5%10%25%15%1
2242
16th to endNight
45%6%14%22%10%
2675
November1st to 15thNight
44%6%10%22%14%1
2666
16th to endNight
50%6%15%18%6%
2817
December1st to 15thNight
56%7%9%17%7%
2940
16th to endNight
62%6%9%14%7%
3136

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
17%11%28%32%10%
180
16th to endDay
17%135%36%8%
192
February1st to 15thDay
19%8%37%26%7%
180
16th to endDay
25%5%32%30%5%
159
March1st to 15thDay
16%7%34%30%10%
180
16th to endDay
21%324%32%15%2
374
April1st to 15thDay
29%325%29%10%1
390
16th to endDay
21%320%32%16%5%
379
May1st to 15thDay
24%119%35%16%2
470
16th to endDay
15%216%32%26%6%
677
June1st to 15thDay
14%113%38%28%3
645
16th to endDay
12%212%40%27%5%
645
July1st to 15thDay
7%9%31%39%11%
625
16th to endDay
7%18%37%35%8%
675
August1st to 15thDay
7%16%36%36%11%
545
16th to endDay
14%110%33%30%9%
460
September1st to 15thDay
12%211%29%30%13%
435
16th to endDay
10%5%16%26%29%11%
378
October1st to 15thDay
24%5%17%31%17%4
274
16th to endDay
16%6%31%34%10%1
192
November1st to 15thDay
14%9%25%32%17%1
180
16th to endDay
20%8%34%27%9%
180
December1st to 15thDay
18%8%36%22%12%1
180
16th to endDay
29%12%34%19%3
192
January1st to 15thNight
22%12%34%23%6%
1050
16th to endNight
18%11%36%27%5%
1120
February1st to 15thNight
20%9%33%30%5%
956
16th to endNight
22%8%31%27%8%
735
March1st to 15thNight
17%7%29%32%11%1
840
16th to endNight
17%326%34%15%1
742
April1st to 15thNight
25%5%27%30%9%1
629
16th to endNight
21%319%36%16%2
624
May1st to 15thNight
22%216%38%17%2
630
16th to endNight
13%214%36%26%6%
659
June1st to 15thNight
14%111%40%26%4
630
16th to endNight
12%211%38%30%4
630
July1st to 15thNight
5%28%33%41%8%
600
16th to endNight
6%18%40%35%7%
660
August1st to 15thNight
6%17%40%35%8%
620
16th to endNight
11%212%33%33%7%
669
September1st to 15thNight
11%216%30%27%10%
639
16th to endNight
13%317%27%30%8%
782
October1st to 15thNight
21%6%19%29%19%2
780
16th to endNight
22%9%29%27%10%1
832
November1st to 15thNight
18%8%31%28%11%1
820
16th to endNight
20%11%33%26%8%
927
December1st to 15thNight
24%14%32%22%5%
1050
16th to endNight
27%10%34%21%4
1120
Page generated at 2019-09-17 20:12:15. Version ac04

Copyright 2019 A. Danko


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