Harrisburg
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Harrisburg clear sky chart from 2005-11-05 to 2018-02-22.

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
34%
15731
19%
48929
10%
15692
44%
15692
21%
31648

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%
778
17%
2680
7%
776
34%
776
14%
1765
January16th to endNight
19%
832
21%
2704
6%
832
37%
832
17%
1748
February1st to 15thNight
18%
764
16%
2482
4%
761
33%
761
14%
1674
February16th to endNight
15%
659
23%
2008
6%
659
35%
659
16%
1323
March1st to 15thNight
21%
720
19%
2028
7%
720
34%
720
19%
1379
March16th to endNight
20%
768
21%
2076
7%
768
32%
768
21%
1397
April1st to 15thNight
22%
718
16%
1796
4%
718
30%
718
23%
1255
April16th to endNight
31%
720
18%
1800
4%
720
39%
720
29%
1202
May1st to 15thNight
35%
492
17%
1572
9%
492
44%
492
19%
1056
May16th to endNight
45%
374
17%
1497
14%
374
53%
374
19%
929
June1st to 15thNight
48%
360
17%
1440
14%
360
57%
360
22%
859
June16th to endNight
48%
360
17%
1440
17%
360
56%
360
26%
820
July1st to 15thNight
51%
340
13%
1360
16%
340
54%
340
19%
853
July16th to endNight
64%
483
16%
1516
14%
452
68%
452
29%
888
August1st to 15thNight
61%
539
19%
1609
15%
536
64%
536
31%
996
August16th to endNight
63%
747
21%
1893
12%
747
65%
747
32%
1235
September1st to 15thNight
51%
720
24%
1800
12%
720
56%
720
33%
1175
September16th to endNight
52%
717
25%
1970
20%
717
56%
717
30%
1274
October1st to 15thNight
40%
720
21%
2160
16%
720
48%
720
24%
1396
October16th to endNight
33%
768
25%
2304
13%
768
48%
768
25%
1437
November1st to 15thNight
34%
760
22%
2454
12%
760
47%
760
24%
1500
November16th to endNight
26%
780
20%
2698
9%
780
42%
780
17%
1714
December1st to 15thNight
23%
780
14%
2730
5%
780
34%
780
13%
1861
December16th to endNight
19%
832
16%
2912
3%
832
35%
832
14%
1912

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
15%5%25%5%35%5%5%7%38%
49317
Night
15%5%2442445%7%41%
49109
Cloud CoverDay
14%6%25%5%3445%7%39%
49327
Night
15%5%25%43445%7%41%
49114
TransparencyDay
42%6%12%21%14%2
49015
Night
41%6%11%22%15%2
48929
SeeingDay
20%12%26%21%14%5%
6100
Night
19%12%28%26%11%
15734

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
16%6%35%5%345%6%6%36%
1585
16th to endDay
14%8%47%5%35%5%5%6%33%
1872
February1st to 15thDay
15%9%36%5%25%45%7%34%
1710
16th to endDay
15%6%36%6%25%446%36%
1610
March1st to 15thDay
16%5%245%26%45%7%38%
1921
16th to endDay
18%7%25%42435%7%37%
2148
April1st to 15thDay
16%7%35%43445%6%39%
2152
16th to endDay
17%4245%24446%42%
2160
May1st to 15thDay
19%5%245%35%447%35%
2387
16th to endDay
15%6%25%5%345%5%7%36%
2618
June1st to 15thDay
13%4245%36%6%5%8%38%
2520
16th to endDay
11%325%5%345%6%10%40%
2520
July1st to 15thDay
9%425%6%46%6%6%9%36%
2520
16th to endDay
8%425%6%46%5%6%9%39%
2544
August1st to 15thDay
11%5%25%5%36%6%7%9%34%
2340
16th to endDay
13%4234245%6%8%43%
2296
September1st to 15thDay
15%5%2442445%6%45%
2160
16th to endDay
15%42432445%6%45%
1987
October1st to 15thDay
18%5%24323447%43%
1800
16th to endDay
15%5%245%35%45%7%41%
1920
November1st to 15thDay
16%6%23323447%44%
1734
16th to endDay
19%424435%346%40%
1589
December1st to 15thDay
17%7%46%5%345%5%6%33%
1560
16th to endDay
18%6%26%5%36%45%7%32%
1664
January1st to 15thNight
16%6%36%43445%7%37%
2680
16th to endNight
15%8%35%4235%5%6%39%
2704
February1st to 15thNight
15%8%36%43445%7%36%
2480
16th to endNight
14%6%35%43445%6%40%
2008
March1st to 15thNight
17%6%345%24446%40%
2016
16th to endNight
18%6%2442445%6%40%
2076
April1st to 15thNight
16%6%35%5%2436%8%36%
1796
16th to endNight
17%5%24324347%44%
1800
May1st to 15thNight
20%5%2442445%7%38%
1572
16th to endNight
14%5%25%5%35%46%8%39%
1495
June1st to 15thNight
14%4144245%5%8%43%
1440
16th to endNight
10%4144345%6%11%42%
1440
July1st to 15thNight
10%435%5%35%5%6%8%40%
1440
16th to endNight
8%3235%36%5%7%9%44%
1621
August1st to 15thNight
10%4144345%6%9%43%
1620
16th to endNight
11%424435%46%7%45%
1893
September1st to 15thNight
14%42342436%6%47%
1800
16th to endNight
14%415%5%24446%46%
1970
October1st to 15thNight
20%5%14423345%44%
2160
16th to endNight
16%5%23333446%45%
2304
November1st to 15thNight
13%5%35%5%23345%47%
2454
16th to endNight
16%6%245%3445%6%40%
2698
December1st to 15thNight
18%6%35%5%35%46%7%33%
2730
16th to endNight
16%7%25%5%245%5%8%36%
2912

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
15%6%36%5%2446%6%36%
1585
16th to endDay
13%8%46%5%35%46%6%34%
1872
February1st to 15thDay
15%8%36%435%5%5%7%34%
1710
16th to endDay
15%7%37%6%24447%36%
1610
March1st to 15thDay
15%5%25%5%35%447%39%
1932
16th to endDay
18%7%25%42435%8%37%
2147
April1st to 15thDay
16%6%35%434446%39%
2152
16th to endDay
17%5%15%424446%43%
2160
May1st to 15thDay
18%6%245%36%45%7%35%
2387
16th to endDay
14%7%25%5%35%5%6%7%36%
2618
June1st to 15thDay
12%5%24436%6%6%8%38%
2520
16th to endDay
11%425%4345%6%10%41%
2520
July1st to 15thDay
8%5%25%6%36%5%7%10%36%
2520
16th to endDay
7%5%25%6%5%5%6%6%10%38%
2544
August1st to 15thDay
12%5%26%5%35%7%7%8%35%
2340
16th to endDay
13%41443446%8%43%
2296
September1st to 15thDay
15%5%2343345%7%45%
2160
16th to endDay
14%5%24334446%44%
1987
October1st to 15thDay
18%5%14323446%44%
1800
16th to endDay
15%5%145%3445%7%42%
1920
November1st to 15thDay
16%6%2332335%7%45%
1734
16th to endDay
19%434434446%41%
1589
December1st to 15thDay
17%7%26%6%245%5%7%34%
1560
16th to endDay
18%6%35%5%36%45%8%33%
1664
January1st to 15thNight
16%7%26%4335%5%7%36%
2680
16th to endNight
15%8%35%42345%7%39%
2704
February1st to 15thNight
15%7%36%5%3445%6%37%
2473
16th to endNight
14%6%35%5%24447%40%
2008
March1st to 15thNight
17%6%34434446%40%
2028
16th to endNight
17%6%2442445%6%41%
2076
April1st to 15thNight
16%6%26%5%35%25%8%37%
1796
16th to endNight
17%424323447%44%
1800
May1st to 15thNight
18%6%24424448%38%
1572
16th to endNight
13%6%245%3446%7%40%
1495
June1st to 15thNight
14%3144245%5%8%44%
1440
16th to endNight
9%4144345%7%10%43%
1440
July1st to 15thNight
10%425%6%45%6%6%9%39%
1440
16th to endNight
8%413445%6%7%10%44%
1621
August1st to 15thNight
9%5%245%35%5%7%8%44%
1620
16th to endNight
10%424435%5%6%8%45%
1893
September1st to 15thNight
13%5%2333435%6%47%
1800
16th to endNight
14%4245%24436%46%
1970
October1st to 15thNight
19%6%14423335%44%
2160
16th to endNight
16%423324447%45%
2304
November1st to 15thNight
13%5%25%5%23345%47%
2454
16th to endNight
16%5%25%42445%6%40%
2698
December1st to 15thNight
18%6%35%435%5%5%7%33%
2730
16th to endNight
16%6%25%425%5%5%8%36%
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
45%5%13%20%11%2
1586
16th to endDay
49%5%13%19%9%1
1872
February1st to 15thDay
48%6%11%20%10%2
1712
16th to endDay
48%412%22%10%1
1610
March1st to 15thDay
44%6%13%22%11%1
1932
16th to endDay
46%5%9%20%15%2
2148
April1st to 15thDay
44%5%11%20%15%3
2152
16th to endDay
41%5%9%20%18%5%
2160
May1st to 15thDay
47%6%8%20%14%1
2387
16th to endDay
44%8%11%20%12%1
2622
June1st to 15thDay
40%9%11%22%14%1
2520
16th to endDay
37%8%14%24%13%2
2520
July1st to 15thDay
40%9%11%19%16%2
2371
16th to endDay
38%8%13%23%15%1
2386
August1st to 15thDay
41%9%13%18%15%1
2327
16th to endDay
37%6%10%25%17%2
2296
September1st to 15thDay
38%6%13%18%20%3
2160
16th to endDay
38%5%9%20%22%3
1987
October1st to 15thDay
40%6%11%23%15%2
1800
16th to endDay
40%5%11%26%14%
1920
November1st to 15thDay
38%414%21%16%4
1734
16th to endDay
43%410%27%12%1
1589
December1st to 15thDay
48%6%15%19%9%
1560
16th to endDay
48%6%14%19%9%
1664
January1st to 15thNight
45%6%12%19%12%2
2680
16th to endNight
43%5%12%25%12%1
2704
February1st to 15thNight
46%6%13%20%11%1
2482
16th to endNight
43%5%9%24%15%1
2008
March1st to 15thNight
44%5%11%24%12%1
2028
16th to endNight
43%5%10%21%16%2
2076
April1st to 15thNight
44%411%19%16%2
1796
16th to endNight
39%5%10%20%17%6%
1800
May1st to 15thNight
45%7%9%19%15%2
1572
16th to endNight
41%7%13%19%15%2
1497
June1st to 15thNight
37%8%12%22%18%
1440
16th to endNight
34%7%13%25%17%1
1440
July1st to 15thNight
40%9%12%19%14%3
1360
16th to endNight
32%8%16%21%17%2
1516
August1st to 15thNight
35%7%12%24%19%1
1609
16th to endNight
35%7%10%22%20%3
1893
September1st to 15thNight
35%6%11%20%22%3
1800
16th to endNight
39%47%21%23%3
1970
October1st to 15thNight
42%49%24%15%2
2160
16th to endNight
37%6%9%29%16%1
2304
November1st to 15thNight
38%410%23%16%5%
2454
16th to endNight
42%5%9%24%16%1
2698
December1st to 15thNight
49%6%12%19%10%1
2730
16th to endNight
45%6%16%21%9%
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
35%23%27%10%21
98
16th to endDay
30%24%35%9%
144
February1st to 15thDay
32%30%29%7%
135
16th to endDay
27%19%36%14%1
231
March1st to 15thDay
25%18%30%21%5%
270
16th to endDay
22%23%33%13%42
288
April1st to 15thDay
22%24%25%14%10%2
270
16th to endDay
20%11%31%17%14%5%
270
May1st to 15thDay
32%15%23%13%12%2
288
16th to endDay
24%8%22%21%16%6%
331
June1st to 15thDay
18%10%27%24%16%3
315
16th to endDay
15%7%33%26%13%3
315
July1st to 15thDay
13%425%27%24%4
305
16th to endDay
8%323%31%24%7%
326
August1st to 15thDay
17%220%27%21%10%
313
16th to endDay
13%215%33%18%16%
332
September1st to 15thDay
18%6%23%19%20%11%
315
16th to endDay
18%6%17%24%19%13%
314
October1st to 15thDay
25%5%16%26%19%6%
315
16th to endDay
17%16%32%19%13%1
336
November1st to 15thDay
19%13%27%24%13%1
284
16th to endDay
25%19%34%14%6%
119
December1st to 15thDay
25%23%28%12%6%3
90
16th to endDay
32%19%36%10%1
96
January1st to 15thNight
23%18%31%22%3
780
16th to endNight
21%21%33%22%1
832
February1st to 15thNight
23%20%31%23%1
764
16th to endNight
24%21%33%17%2
659
March1st to 15thNight
24%16%33%22%3
720
16th to endNight
21%17%34%18%6%
768
April1st to 15thNight
21%18%33%20%4
718
16th to endNight
20%11%32%25%9%
720
May1st to 15thNight
22%9%28%29%10%
492
16th to endNight
16%6%23%33%18%
375
June1st to 15thNight
14%328%31%21%
360
16th to endNight
10%132%40%14%
360
July1st to 15thNight
15%222%39%20%1
340
16th to endNight
9%218%42%24%2
483
August1st to 15thNight
14%116%39%26%2
539
16th to endNight
13%213%35%30%3
747
September1st to 15thNight
16%5%22%31%22%1
720
16th to endNight
16%5%20%24%28%4
717
October1st to 15thNight
23%7%22%26%17%2
720
16th to endNight
20%14%28%25%10%
768
November1st to 15thNight
15%15%30%27%10%1
760
16th to endNight
22%18%28%21%8%
780
December1st to 15thNight
24%16%31%21%6%
780
16th to endNight
21%19%33%23%1
832
Page generated at 2018-02-23 11:21:40. Version ac04

Copyright 2018 A. Danko


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