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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 2020-06-03.

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
40%
19784
17%
57796
10%
19742
46%
19742
22%
39546

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%
1125
12%
3136
3%
1120
28%
1120
14%
2431
January16th to endNight
21%
1200
12%
3360
4%
1200
28%
1200
15%
2606
February1st to 15thNight
23%
1023
14%
2812
3%
1023
32%
1023
18%
2059
February16th to endNight
26%
791
18%
2373
7%
791
37%
791
17%
1696
March1st to 15thNight
35%
900
15%
2700
8%
900
41%
900
21%
1852
March16th to endNight
42%
795
18%
2520
13%
795
48%
795
21%
1716
April1st to 15thNight
35%
674
15%
2247
10%
674
43%
674
19%
1551
April16th to endNight
46%
669
20%
2104
16%
669
51%
669
24%
1382
May1st to 15thNight
46%
675
16%
1954
12%
675
50%
675
22%
1365
May16th to endNight
56%
706
15%
1882
11%
705
58%
705
30%
1241
June1st to 15thNight
63%
637
16%
1700
11%
637
65%
637
34%
1080
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
57%
837
24%
2310
17%
837
61%
837
34%
1429
October1st to 15thNight
45%
840
20%
2414
14%
840
51%
840
26%
1593
October16th to endNight
34%
896
16%
2880
10%
896
43%
896
20%
1934
November1st to 15thNight
34%
880
20%
2861
14%
880
42%
880
21%
1877
November16th to endNight
27%
993
15%
3018
7%
993
36%
993
17%
2177
December1st to 15thNight
21%
1125
11%
3150
4%
1125
27%
1125
13%
2433
December16th to endNight
19%
1200
11%
3360
3%
1200
27%
1200
12%
2648

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%37%
58619
Night
14%8%35%5%2445%6%38%
57964
Cloud CoverDay
12%7%36%5%35%5%5%7%37%
58628
Night
14%8%35%5%3445%6%37%
57969
TransparencyDay
44%6%13%22%11%1
58305
Night
45%6%11%22%12%1
57796
SeeingDay
16%318%32%22%5%
9689
Night
18%6%24%30%16%2
19788

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%8%27%
1792
16th to endDay
12%13%5%10%7%445%6%7%22%
1920
February1st to 15thDay
13%11%5%8%5%2445%6%30%
2038
16th to endDay
12%11%48%5%25%5%5%6%33%
1980
March1st to 15thDay
12%8%46%5%36%5%47%35%
2240
16th to endDay
14%8%36%5%35%5%5%6%33%
2771
April1st to 15thDay
18%9%46%5%25%5%5%6%30%
2691
16th to endDay
18%7%35%5%34446%36%
2790
May1st to 15thDay
16%7%26%435%45%7%34%
2983
16th to endDay
12%5%25%435%5%5%8%41%
3289
June1st to 15thDay
11%5%25%5%35%5%5%8%40%
2969
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
9%5%25%5%25%46%8%42%
2310
October1st to 15thDay
18%6%35%424445%39%
2202
16th to endDay
16%6%26%6%445%6%7%34%
2048
November1st to 15thDay
13%8%37%5%3445%7%36%
1987
16th to endDay
15%10%36%5%3445%8%31%
1928
December1st to 15thDay
17%10%36%436%6%5%8%26%
1800
16th to endDay
17%13%5%8%5%35%5%6%6%21%
1920
January1st to 15thNight
15%13%47%6%2446%5%29%
3136
16th to endNight
13%10%5%9%6%345%7%7%25%
3360
February1st to 15thNight
14%12%45%5%2445%5%34%
2810
16th to endNight
15%11%37%5%3444434%
2373
March1st to 15thNight
14%7%45%5%25%45%6%37%
2687
16th to endNight
14%7%36%435%446%37%
2520
April1st to 15thNight
20%9%34424445%35%
2247
16th to endNight
18%6%35%423345%40%
2104
May1st to 15thNight
19%7%25%5%25%45%7%33%
1954
16th to endNight
12%5%25%5%15%5%5%9%40%
1880
June1st to 15thNight
13%4243245%6%8%44%
1700
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%42442345%7%49%
2310
October1st to 15thNight
17%6%24423446%42%
2414
16th to endNight
17%7%245%3445%7%37%
2880
November1st to 15thNight
14%9%25%425%436%40%
2861
16th to endNight
17%9%36%5%3445%6%33%
3018
December1st to 15thNight
19%11%46%5%345%5%7%26%
3150
16th to endNight
19%12%47%5%36%446%24%
3360

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%26%
1792
16th to endDay
12%13%6%10%7%346%6%7%21%
1920
February1st to 15thDay
13%11%6%8%6%245%5%6%29%
2038
16th to endDay
12%10%48%5%35%5%5%6%33%
1980
March1st to 15thDay
13%8%47%5%3445%7%34%
2250
16th to endDay
14%8%46%6%345%5%7%33%
2770
April1st to 15thDay
18%9%46%5%35%5%5%6%30%
2691
16th to endDay
18%7%25%5%34446%36%
2790
May1st to 15thDay
16%7%35%435%46%7%34%
2983
16th to endDay
12%5%245%345%6%8%40%
3289
June1st to 15thDay
11%5%25%5%35%5%6%8%40%
2969
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%26%5%245%6%9%42%
2310
October1st to 15thDay
18%6%35%42445%6%38%
2202
16th to endDay
15%7%27%6%345%6%7%33%
2048
November1st to 15thDay
12%8%47%5%25%45%7%35%
1987
16th to endDay
15%10%36%6%3445%8%31%
1928
December1st to 15thDay
17%11%46%5%46%46%8%24%
1800
16th to endDay
17%14%5%9%5%35%5%5%6%20%
1920
January1st to 15thNight
16%12%5%7%5%345%6%5%27%
3136
16th to endNight
13%10%5%8%6%35%6%7%7%24%
3360
February1st to 15thNight
14%11%5%6%42445%5%33%
2803
16th to endNight
15%11%37%5%3445%434%
2373
March1st to 15thNight
14%7%46%6%35%45%6%36%
2700
16th to endNight
14%8%35%435%5%46%37%
2520
April1st to 15thNight
20%9%35%424445%35%
2247
16th to endNight
18%6%25%423446%40%
2104
May1st to 15thNight
19%7%36%43446%7%32%
1953
16th to endNight
12%6%26%425%5%410%40%
1880
June1st to 15thNight
12%4244245%5%8%44%
1700
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
11%5%1442445%6%48%
2310
October1st to 15thNight
17%7%2442345%6%42%
2414
16th to endNight
17%7%35%42345%6%37%
2880
November1st to 15thNight
14%9%34435%445%40%
2861
16th to endNight
17%9%35%5%35%5%5%6%32%
3018
December1st to 15thNight
18%12%46%6%25%5%6%7%24%
3150
16th to endNight
19%12%48%5%35%445%24%
3360

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%10%10%17%7%
1793
16th to endDay
59%9%10%14%5%
1920
February1st to 15thDay
55%6%9%19%7%1
2040
16th to endDay
51%5%11%19%10%1
1980
March1st to 15thDay
48%5%13%20%9%1
2250
16th to endDay
49%5%16%19%7%
2771
April1st to 15thDay
52%5%12%17%10%
2691
16th to endDay
48%412%17%13%3
2790
May1st to 15thDay
48%5%12%23%9%1
2983
16th to endDay
39%6%13%25%13%1
3293
June1st to 15thDay
40%5%12%27%12%1
2969
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
37%6%15%28%11%
2310
October1st to 15thDay
46%411%23%12%
2202
16th to endDay
47%6%14%21%9%
2048
November1st to 15thDay
46%5%13%22%10%1
1987
16th to endDay
51%6%15%20%5%
1928
December1st to 15thDay
56%8%10%16%6%
1800
16th to endDay
61%6%11%13%5%
1920
January1st to 15thNight
55%8%8%15%10%
3136
16th to endNight
55%9%12%16%6%
3360
February1st to 15thNight
52%5%9%20%10%1
2812
16th to endNight
52%48%20%11%1
2373
March1st to 15thNight
47%5%13%20%11%1
2700
16th to endNight
47%5%11%24%9%1
2520
April1st to 15thNight
50%47%19%16%1
2247
16th to endNight
45%410%20%14%4
2104
May1st to 15thNight
48%411%21%12%1
1954
16th to endNight
39%5%14%23%13%3
1882
June1st to 15thNight
36%5%11%29%16%1
1700
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
34%5%10%34%13%1
2310
October1st to 15thNight
42%5%10%25%15%1
2414
16th to endNight
45%6%13%22%10%
2880
November1st to 15thNight
44%5%10%22%14%2
2861
16th to endNight
51%6%15%19%6%
3018
December1st to 15thNight
56%8%10%17%6%
3150
16th to endNight
61%6%10%14%6%
3360

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
18%10%32%29%8%
225
16th to endDay
19%230%34%12%1
240
February1st to 15thDay
20%8%37%24%8%
225
16th to endDay
22%6%31%33%4
201
March1st to 15thDay
17%8%33%31%9%
225
16th to endDay
23%324%30%14%2
435
April1st to 15thDay
26%425%30%12%
450
16th to endDay
23%221%32%15%4
439
May1st to 15thDay
22%120%36%16%2
535
16th to endDay
17%214%31%26%7%
757
June1st to 15thDay
14%113%38%28%3
656
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
12%417%27%28%10%
434
October1st to 15thDay
24%5%20%28%16%3
327
16th to endDay
16%7%28%36%10%
240
November1st to 15thDay
15%8%24%34%16%
225
16th to endDay
23%7%33%26%9%
225
December1st to 15thDay
19%9%36%23%10%
225
16th to endDay
26%10%34%22%5%
240
January1st to 15thNight
22%13%35%22%5%
1125
16th to endNight
19%11%35%26%7%
1200
February1st to 15thNight
20%9%35%29%5%
1026
16th to endNight
22%8%32%27%8%
791
March1st to 15thNight
17%7%29%32%10%1
900
16th to endNight
17%326%35%15%1
795
April1st to 15thNight
25%5%26%30%10%1
674
16th to endNight
21%319%37%15%2
669
May1st to 15thNight
21%316%38%17%2
675
16th to endNight
14%214%34%27%6%
707
June1st to 15thNight
14%111%41%26%4
637
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
14%317%26%29%8%
837
October1st to 15thNight
22%6%20%28%19%2
840
16th to endNight
22%9%28%28%10%1
896
November1st to 15thNight
19%8%32%27%10%1
880
16th to endNight
21%11%31%26%8%
993
December1st to 15thNight
24%14%32%22%5%
1125
16th to endNight
26%10%34%23%4
1200
Page generated at 2020-06-04 02:18:55. Version ac04

Copyright 2020 A. Danko


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