Greencastle
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Greencastle clear sky chart from 2005-11-06 to 2024-12-06.

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 Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(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

By Month

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 Forecast	Data Points
Cloud Cover	Day	15% 7% 2 6% 5% 4 5% 4 6% 7% 39%	101533
	Night	15% 7% 2 6% 4 4 4 4 6% 7% 40%	98116
Transparency	Day	23% 48% 7% 13% 8% 1	105172
	Night	23% 48% 7% 13% 8% 1	102616
Seeing	Day	20% 15% 27% 22% 13% 4	14958
	Night	17% 13% 28% 29% 12% 1	24497

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	17% 9% 3 8% 5% 4 4 3 5% 5% 37%	2585
	11th to 20th	Day	15% 13% 4 9% 5% 5% 6% 4 6% 5% 29%	2840
	21st to end	Day	17% 12% 4 7% 5% 5% 4 3 5% 6% 30%	3124
February	1st to 10th	Day	15% 10% 3 8% 5% 4 4 4 5% 7% 35%	1710
	11th to 20th	Day	14% 10% 3 7% 5% 5% 4 3 6% 7% 37%	1669
	21st to end	Day	19% 10% 3 7% 5% 4 4 3 5% 4 37%	1570
March	1st to 10th	Day	22% 9% 2 6% 5% 4 5% 4 5% 7% 33%	3422
	11th to 20th	Day	11% 7% 2 5% 5% 4 5% 4 5% 7% 44%	3480
	21st to end	Day	18% 9% 2 6% 4 3 4 3 5% 6% 39%	3841
April	1st to 10th	Day	15% 8% 2 7% 6% 3 5% 4 6% 8% 35%	2280
	11th to 20th	Day	14% 7% 2 6% 5% 5% 5% 4 5% 6% 43%	2254
	21st to end	Day	19% 6% 2 5% 5% 4 4 3 6% 7% 39%	2307
May	1st to 10th	Day	27% 6% 2 6% 4 4 4 4 5% 7% 30%	4082
	11th to 20th	Day	24% 7% 2 6% 4 4 5% 3 6% 7% 31%	4270
	21st to end	Day	12% 5% 2 5% 5% 4 5% 4 6% 8% 44%	4823
June	1st to 10th	Day	13% 5% 2 4 4 5% 6% 5% 7% 9% 42%	2660
	11th to 20th	Day	12% 5% 2 6% 5% 4 5% 5% 7% 10% 39%	2660
	21st to end	Day	10% 5% 2 5% 5% 4 4 4 7% 10% 45%	2660
July	1st to 10th	Day	6% 4 1 5% 6% 5% 6% 5% 7% 10% 44%	4440
	11th to 20th	Day	7% 5% 2 5% 4 5% 5% 4 8% 10% 43%	4312
	21st to end	Day	11% 7% 3 7% 5% 5% 5% 4 6% 8% 39%	4466
August	1st to 10th	Day	16% 7% 3 7% 4 5% 5% 4 7% 9% 35%	4104
	11th to 20th	Day	10% 5% 2 6% 4 5% 6% 4 7% 9% 42%	3953
	21st to end	Day	12% 4 2 5% 3 4 5% 4 5% 7% 48%	4180
September	1st to 10th	Day	16% 5% 2 5% 4 4 4 3 4 6% 47%	2280
	11th to 20th	Day	12% 5% 2 5% 3 3 4 3 6% 8% 49%	2275
	21st to end	Day	21% 7% 2 5% 4 4 4 3 5% 7% 38%	1984
October	1st to 10th	Day	16% 5% 2 6% 4 4 3 4 4 7% 46%	1900
	11th to 20th	Day	16% 5% 2 5% 4 4 4 4 4 7% 45%	1900
	21st to end	Day	15% 6% 2 5% 3 3 4 3 5% 6% 46%	2090
November	1st to 10th	Day	11% 6% 2 5% 4 3 4 3 5% 6% 50%	1864
	11th to 20th	Day	15% 6% 2 6% 4 4 4 4 5% 7% 44%	1706
	21st to end	Day	15% 7% 3 5% 6% 4 4 4 5% 7% 40%	1600
December	1st to 10th	Day	19% 9% 3 7% 4 5% 5% 4 6% 7% 32%	1560
	11th to 20th	Day	17% 9% 3 5% 5% 4 4 3 6% 6% 36%	1910
	21st to end	Day	20% 9% 3 9% 6% 4 5% 4 6% 7% 28%	2772
January	1st to 10th	Night	13% 10% 3 9% 5% 5% 5% 4 5% 6% 36%	4359
	11th to 20th	Night	17% 10% 3 7% 5% 5% 4 4 4 6% 35%	4120
	21st to end	Night	21% 10% 3 8% 5% 4 4 3 5% 6% 32%	4532
February	1st to 10th	Night	16% 8% 3 6% 5% 4 4 4 6% 6% 38%	2470
	11th to 20th	Night	17% 9% 3 7% 4 4 5% 4 6% 6% 36%	2395
	21st to end	Night	17% 10% 3 6% 5% 4 4 4 6% 8% 34%	1884
March	1st to 10th	Night	21% 8% 2 5% 5% 4 4 3 4 6% 37%	3428
	11th to 20th	Night	13% 7% 3 6% 4 4 3 4 6% 6% 45%	3480
	21st to end	Night	14% 8% 2 6% 4 4 4 3 4 5% 47%	3790
April	1st to 10th	Night	17% 9% 3 7% 5% 5% 4 4 6% 6% 35%	1900
	11th to 20th	Night	14% 6% 1 6% 5% 4 4 3 6% 8% 43%	1875
	21st to end	Night	17% 4 2 5% 4 5% 4 4 6% 7% 42%	1890
May	1st to 10th	Night	27% 7% 2 7% 5% 3 4 3 5% 7% 31%	2813
	11th to 20th	Night	23% 7% 3 7% 4 4 4 3 5% 7% 32%	2605
	21st to end	Night	13% 5% 2 5% 4 5% 6% 4 6% 9% 41%	2732
June	1st to 10th	Night	12% 4 2 5% 4 4 4 4 6% 7% 47%	1520
	11th to 20th	Night	12% 5% 2 7% 5% 4 5% 4 6% 9% 41%	1520
	21st to end	Night	9% 5% 1 5% 4 5% 4 4 6% 10% 45%	1520
July	1st to 10th	Night	8% 4 2 5% 4 6% 6% 5% 7% 11% 43%	2520
	11th to 20th	Night	7% 5% 2 7% 5% 5% 5% 5% 8% 10% 40%	2643
	21st to end	Night	11% 7% 2 7% 5% 5% 5% 4 7% 8% 39%	3087
August	1st to 10th	Night	15% 7% 2 8% 4 5% 5% 4 6% 9% 34%	2825
	11th to 20th	Night	11% 6% 3 7% 5% 4 4 4 6% 8% 43%	2843
	21st to end	Night	13% 5% 2 6% 4 4 4 4 5% 8% 46%	3476
September	1st to 10th	Night	14% 5% 2 5% 4 4 4 3 5% 7% 47%	1900
	11th to 20th	Night	11% 6% 2 5% 3 4 3 3 5% 6% 52%	1900
	21st to end	Night	18% 7% 2 6% 3 5% 5% 3 5% 6% 41%	2194
October	1st to 10th	Night	19% 5% 2 5% 4 3 4 3 5% 6% 44%	2280
	11th to 20th	Night	14% 5% 2 5% 4 4 4 3 5% 6% 49%	2280
	21st to end	Night	16% 6% 2 5% 3 4 4 3 6% 6% 46%	2508
November	1st to 10th	Night	10% 6% 2 6% 3 3 4 3 5% 5% 53%	2431
	11th to 20th	Night	15% 8% 2 5% 4 4 4 3 6% 6% 43%	2690
	21st to end	Night	14% 6% 3 6% 5% 5% 4 4 5% 8% 41%	2800
December	1st to 10th	Night	16% 9% 3 7% 5% 4 4 4 5% 6% 37%	2737
	11th to 20th	Night	18% 8% 3 5% 5% 5% 4 4 6% 6% 36%	3285
	21st to end	Night	18% 8% 3 7% 5% 5% 6% 5% 7% 8% 29%	4884

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	30% 39% 8% 15% 6% 2	2586
	11th to 20th	Day	35% 40% 5% 10% 7% 2	2840
	21st to end	Day	35% 43% 4 14% 3 1	3124
February	1st to 10th	Day	19% 66% 5% 6% 3 1	1710
	11th to 20th	Day	17% 64% 3 8% 6% 1	1678
	21st to end	Day	18% 65% 4 8% 5% 1	1570
March	1st to 10th	Day	34% 44% 6% 10% 5% 1	3422
	11th to 20th	Day	19% 43% 7% 20% 9% 1	3480
	21st to end	Day	26% 42% 7% 13% 10% 2	3841
April	1st to 10th	Day	19% 66% 4 5% 5% 1	2280
	11th to 20th	Day	13% 67% 4 9% 5% 1	2254
	21st to end	Day	17% 66% 3 9% 5%	2307
May	1st to 10th	Day	35% 43% 5% 12% 4	4120
	11th to 20th	Day	32% 44% 10% 12% 2	4274
	21st to end	Day	18% 45% 10% 15% 11% 1	4837
June	1st to 10th	Day	14% 67% 4 9% 5%	2660
	11th to 20th	Day	13% 67% 5% 8% 6%	2660
	21st to end	Day	13% 64% 5% 11% 6%	2660
July	1st to 10th	Day	22% 41% 11% 16% 7% 3	4370
	11th to 20th	Day	23% 40% 11% 18% 9%	4237
	21st to end	Day	28% 37% 6% 15% 12% 1	4324
August	1st to 10th	Day	30% 41% 9% 16% 4	4091
	11th to 20th	Day	24% 39% 9% 19% 9%	3992
	21st to end	Day	21% 39% 7% 18% 14%	4180
September	1st to 10th	Day	16% 61% 6% 9% 8% 1	2280
	11th to 20th	Day	14% 61% 5% 11% 9% 2	2275
	21st to end	Day	20% 61% 5% 8% 7%	1984
October	1st to 10th	Day	23% 38% 4 14% 18% 4	3160
	11th to 20th	Day	15% 37% 8% 19% 14% 6%	3140
	21st to end	Day	12% 37% 9% 21% 20% 1	3428
November	1st to 10th	Day	18% 56% 6% 9% 8% 2	1864
	11th to 20th	Day	14% 57% 6% 11% 11% 1	1706
	21st to end	Day	17% 58% 7% 13% 4 1	1600
December	1st to 10th	Day	23% 59% 5% 8% 4 1	1560
	11th to 20th	Day	25% 49% 5% 17% 3 1	1906
	21st to end	Day	33% 42% 10% 9% 5%	2772
January	1st to 10th	Night	29% 41% 7% 14% 7% 2	4359
	11th to 20th	Night	30% 39% 8% 16% 6% 1	4120
	21st to end	Night	36% 41% 5% 13% 3 1	4532
February	1st to 10th	Night	16% 66% 6% 9% 3	2470
	11th to 20th	Night	16% 64% 3 9% 7% 1	2397
	21st to end	Night	17% 65% 4 7% 5% 2	1884
March	1st to 10th	Night	33% 43% 5% 15% 4 1	3428
	11th to 20th	Night	19% 42% 6% 25% 7% 1	3480
	21st to end	Night	22% 42% 5% 14% 15% 2	3790
April	1st to 10th	Night	17% 66% 4 8% 4 1	1900
	11th to 20th	Night	13% 67% 4 9% 5% 1	1875
	21st to end	Night	15% 66% 4 10% 5% 1	1890
May	1st to 10th	Night	37% 42% 5% 9% 7% 1	2840
	11th to 20th	Night	33% 45% 8% 11% 3	2606
	21st to end	Night	21% 46% 11% 17% 4 1	2739
June	1st to 10th	Night	14% 66% 4 9% 6%	1520
	11th to 20th	Night	14% 67% 4 10% 5%	1520
	21st to end	Night	12% 65% 6% 10% 6%	1520
July	1st to 10th	Night	21% 41% 14% 10% 10% 4	2480
	11th to 20th	Night	25% 39% 10% 16% 10%	2595
	21st to end	Night	31% 38% 7% 10% 13% 1	2988
August	1st to 10th	Night	33% 40% 11% 13% 3	2814
	11th to 20th	Night	24% 39% 8% 20% 9%	2870
	21st to end	Night	21% 38% 8% 21% 11%	3476
September	1st to 10th	Night	15% 61% 7% 10% 7% 1	1900
	11th to 20th	Night	14% 61% 4 12% 8% 1	1900
	21st to end	Night	20% 61% 4 9% 6%	2194
October	1st to 10th	Night	24% 39% 7% 13% 16% 1	3800
	11th to 20th	Night	15% 37% 6% 17% 21% 4	3779
	21st to end	Night	13% 37% 8% 22% 19% 2	4120
November	1st to 10th	Night	16% 57% 7% 11% 7% 2	2431
	11th to 20th	Night	18% 57% 3 10% 11% 2	2690
	21st to end	Night	17% 58% 6% 11% 6% 1	2800
December	1st to 10th	Night	22% 59% 6% 8% 5%	2737
	11th to 20th	Night	23% 51% 5% 12% 8% 1	3288
	21st to end	Night	31% 43% 10% 11% 5%	4884

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	32% 26% 28% 12% 3 1	200
	11th to 20th	Day	37% 23% 30% 9% 1	270
	21st to end	Day	25% 32% 29% 10% 3	297
February	1st to 10th	Day	31% 26% 31% 10% 3	270
	11th to 20th	Day	39% 27% 30% 4 1	276
	21st to end	Day	31% 22% 29% 16% 2	382
March	1st to 10th	Day	27% 23% 27% 20% 3	460
	11th to 20th	Day	30% 24% 27% 13% 5% 1	460
	21st to end	Day	29% 21% 29% 16% 4 1	506
April	1st to 10th	Day	25% 23% 27% 19% 4 2	460
	11th to 20th	Day	20% 20% 29% 17% 11% 3	452
	21st to end	Day	27% 17% 33% 14% 8% 2	460
May	1st to 10th	Day	26% 19% 29% 16% 7% 3	463
	11th to 20th	Day	22% 16% 28% 18% 12% 3	487
	21st to end	Day	16% 11% 22% 26% 17% 6%	529
June	1st to 10th	Day	14% 13% 30% 20% 19% 4	490
	11th to 20th	Day	14% 9% 31% 26% 15% 5%	490
	21st to end	Day	10% 11% 29% 28% 17% 4	490
July	1st to 10th	Day	9% 5% 24% 31% 20% 11%	485
	11th to 20th	Day	6% 4 25% 30% 26% 8%	484
	21st to end	Day	13% 5% 22% 32% 23% 7%	532
August	1st to 10th	Day	12% 4 21% 29% 25% 10%	486
	11th to 20th	Day	11% 6% 20% 32% 21% 10%	479
	21st to end	Day	9% 7% 20% 31% 22% 11%	539
September	1st to 10th	Day	17% 7% 19% 25% 22% 9%	490
	11th to 20th	Day	12% 4 20% 32% 22% 10%	490
	21st to end	Day	27% 12% 21% 23% 12% 5%	490
October	1st to 10th	Day	19% 9% 24% 26% 17% 5%	490
	11th to 20th	Day	17% 17% 25% 27% 11% 3	490
	21st to end	Day	17% 16% 32% 24% 9% 2	539
November	1st to 10th	Day	16% 14% 31% 25% 12% 2	448
	11th to 20th	Day	22% 19% 29% 22% 7% 1	306
	21st to end	Day	23% 25% 32% 17% 4	200
December	1st to 10th	Day	28% 26% 29% 11% 5% 1	190
	11th to 20th	Day	27% 24% 28% 16% 4	180
	21st to end	Day	25% 19% 33% 19% 4	198
January	1st to 10th	Night	18% 23% 37% 19% 3	760
	11th to 20th	Night	22% 19% 33% 23% 3	760
	21st to end	Night	18% 22% 38% 21% 1	836
February	1st to 10th	Night	19% 20% 33% 25% 2	760
	11th to 20th	Night	24% 27% 31% 17% 1	743
	21st to end	Night	24% 23% 34% 17% 2	628
March	1st to 10th	Night	22% 19% 35% 20% 4	760
	11th to 20th	Night	26% 19% 29% 20% 5%	760
	21st to end	Night	20% 18% 37% 20% 5% 1	836
April	1st to 10th	Night	21% 21% 32% 21% 5%	760
	11th to 20th	Night	16% 16% 32% 28% 8%	751
	21st to end	Night	19% 15% 30% 27% 8%	750
May	1st to 10th	Night	19% 11% 28% 29% 13%	570
	11th to 20th	Night	19% 8% 28% 34% 11%	445
	21st to end	Night	13% 6% 22% 36% 21% 1	411
June	1st to 10th	Night	12% 3 28% 33% 23% 1	380
	11th to 20th	Night	11% 7% 21% 42% 19%	380
	21st to end	Night	8% 4 21% 49% 18%	380
July	1st to 10th	Night	11% 4 16% 39% 28% 3	370
	11th to 20th	Night	8% 3 13% 43% 31% 3	439
	21st to end	Night	9% 2 17% 41% 28% 3	624
August	1st to 10th	Night	11% 2 13% 44% 29% 2	567
	11th to 20th	Night	11% 4 12% 40% 30% 3	596
	21st to end	Night	12% 4 14% 39% 27% 4	836
September	1st to 10th	Night	15% 2 20% 36% 25% 3	760
	11th to 20th	Night	12% 3 18% 35% 28% 4	760
	21st to end	Night	21% 6% 22% 29% 20% 2	760
October	1st to 10th	Night	20% 8% 20% 29% 20% 3	760
	11th to 20th	Night	16% 11% 28% 32% 12% 1	760
	21st to end	Night	19% 11% 29% 31% 10% 1	836
November	1st to 10th	Night	13% 11% 31% 34% 10% 1	780
	11th to 20th	Night	19% 19% 27% 28% 7% 1	800
	21st to end	Night	17% 18% 32% 27% 6% 1	800
December	1st to 10th	Night	21% 18% 33% 22% 6%	783
	11th to 20th	Night	20% 16% 35% 26% 4	760
	21st to end	Night	19% 17% 33% 29% 2	836

Page generated at 2024-12-03 06:45:10. Version ac07

Copyright © 2024 Attilla Danko.