Sweet Run State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Sweet Run State Park clear sky chart from 2005-11-06 to 2025-02-21.

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	14% 6% 2 6% 4 4 5% 4 6% 8% 41%	108679
	Night	14% 6% 2 6% 4 4 4 4 6% 7% 42%	109901
Transparency	Day	39% 7% 12% 24% 16% 3	112319
	Night	38% 6% 12% 24% 17% 3	114400
Seeing	Day	19% 14% 26% 23% 13% 5%	15213
	Night	18% 12% 29% 29% 12% 1	24892

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	14% 4 2 5% 4 5% 6% 4 6% 6% 44%	3761
	11th to 20th	Day	13% 9% 3 7% 4 4 4 4 4 6% 43%	4060
	21st to end	Day	14% 8% 3 7% 4 4 5% 4 5% 6% 41%	4466
February	1st to 10th	Day	14% 9% 3 6% 5% 4 5% 5% 6% 6% 38%	1800
	11th to 20th	Day	17% 8% 2 7% 4 4 4 3 5% 6% 38%	1770
	21st to end	Day	17% 8% 2 7% 5% 4 4 3 4 6% 39%	1570
March	1st to 10th	Day	21% 8% 2 7% 4 5% 4 3 5% 6% 34%	3430
	11th to 20th	Day	10% 5% 2 5% 4 5% 4 4 6% 7% 47%	3480
	21st to end	Day	19% 7% 2 6% 4 4 4 3 5% 6% 39%	3838
April	1st to 10th	Day	13% 6% 3 6% 5% 5% 4 4 6% 8% 39%	2280
	11th to 20th	Day	13% 7% 2 5% 4 4 4 4 5% 7% 45%	2254
	21st to end	Day	18% 6% 2 6% 4 4 4 4 5% 6% 40%	2289
May	1st to 10th	Day	22% 8% 3 6% 4 4 5% 4 6% 8% 30%	4082
	11th to 20th	Day	24% 7% 2 6% 5% 4 4 4 6% 8% 31%	4234
	21st to end	Day	11% 5% 2 6% 4 4 5% 4 6% 9% 44%	4823
June	1st to 10th	Day	12% 5% 2 5% 4 4 5% 4 7% 9% 43%	2660
	11th to 20th	Day	11% 5% 2 6% 4 5% 6% 5% 7% 9% 41%	2660
	21st to end	Day	10% 4 1 5% 4 5% 5% 5% 7% 10% 44%	2660
July	1st to 10th	Day	6% 4 2 5% 6% 6% 6% 5% 8% 10% 42%	4440
	11th to 20th	Day	8% 6% 2 6% 5% 5% 5% 5% 7% 10% 41%	4251
	21st to end	Day	11% 7% 3 7% 6% 5% 5% 4 6% 9% 38%	4466
August	1st to 10th	Day	16% 5% 2 7% 5% 5% 6% 4 6% 9% 35%	4104
	11th to 20th	Day	9% 5% 2 7% 5% 5% 6% 4 7% 9% 41%	3930
	21st to end	Day	10% 5% 2 6% 4 4 5% 4 6% 7% 48%	4180
September	1st to 10th	Day	16% 5% 2 5% 4 4 4 3 5% 6% 46%	2280
	11th to 20th	Day	13% 5% 2 5% 4 4 3 3 6% 8% 48%	2275
	21st to end	Day	21% 6% 2 5% 4 4 4 4 5% 7% 38%	1985
October	1st to 10th	Day	17% 6% 2 6% 3 4 4 3 4 7% 46%	1900
	11th to 20th	Day	16% 4 2 6% 3 3 4 3 5% 6% 48%	1900
	21st to end	Day	14% 5% 2 5% 4 4 3 3 4 6% 50%	2090
November	1st to 10th	Day	11% 7% 2 4 3 3 3 4 5% 7% 51%	1883
	11th to 20th	Day	16% 5% 2 4 3 4 4 3 6% 6% 47%	1728
	21st to end	Day	15% 6% 3 5% 4 4 5% 3 4 7% 44%	1600
December	1st to 10th	Day	12% 6% 2 5% 3 5% 5% 4 6% 7% 45%	2600
	11th to 20th	Day	19% 9% 2 5% 4 4 4 3 4 6% 40%	2990
	21st to end	Day	16% 7% 3 7% 5% 5% 5% 4 6% 9% 33%	3960
January	1st to 10th	Night	11% 7% 2 5% 4 4 4 4 5% 7% 46%	6169
	11th to 20th	Night	14% 6% 2 5% 4 3 4 3 5% 5% 47%	5900
	21st to end	Night	14% 8% 2 6% 3 3 4 3 5% 6% 46%	6490
February	1st to 10th	Night	14% 8% 3 5% 5% 4 4 4 5% 8% 40%	2600
	11th to 20th	Night	16% 8% 3 6% 4 4 4 4 5% 5% 40%	2514
	21st to end	Night	17% 9% 2 6% 5% 4 4 4 5% 6% 38%	1885
March	1st to 10th	Night	20% 8% 2 7% 5% 4 4 3 5% 5% 37%	3420
	11th to 20th	Night	12% 4 2 6% 4 4 5% 3 6% 7% 48%	3480
	21st to end	Night	14% 9% 3 5% 4 4 3 2 4 6% 47%	3793
April	1st to 10th	Night	15% 8% 2 7% 4 5% 5% 4 6% 6% 38%	1900
	11th to 20th	Night	13% 5% 2 6% 5% 4 4 3 6% 8% 43%	1875
	21st to end	Night	17% 4 2 5% 4 5% 4 4 5% 7% 43%	1900
May	1st to 10th	Night	22% 8% 4 7% 4 4 4 3 6% 7% 30%	2820
	11th to 20th	Night	24% 9% 3 7% 4 4 3 3 4 6% 32%	2658
	21st to end	Night	11% 4 2 6% 4 5% 5% 5% 8% 9% 41%	2732
June	1st to 10th	Night	11% 5% 2 5% 4 5% 4 4 6% 9% 44%	1520
	11th to 20th	Night	11% 5% 2 6% 5% 4 5% 5% 8% 9% 40%	1520
	21st to end	Night	9% 5% 2 6% 4 4 5% 4 6% 11% 44%	1520
July	1st to 10th	Night	5% 4 2 8% 5% 6% 7% 5% 8% 10% 39%	2520
	11th to 20th	Night	6% 6% 2 8% 5% 6% 6% 5% 8% 11% 38%	2704
	21st to end	Night	10% 7% 2 7% 5% 5% 6% 5% 6% 8% 39%	3087
August	1st to 10th	Night	15% 5% 2 8% 5% 6% 5% 5% 6% 10% 32%	2825
	11th to 20th	Night	10% 7% 3 7% 5% 5% 5% 4 7% 9% 39%	2867
	21st to end	Night	12% 6% 1 5% 3 4 4 4 6% 8% 47%	3476
September	1st to 10th	Night	15% 6% 1 6% 3 4 4 4 5% 7% 45%	1900
	11th to 20th	Night	11% 6% 2 5% 3 4 3 3 3 6% 52%	1901
	21st to end	Night	20% 7% 3 6% 4 4 4 3 4 6% 41%	2194
October	1st to 10th	Night	20% 5% 2 5% 4 3 4 3 4 6% 46%	2280
	11th to 20th	Night	13% 5% 2 5% 3 3 3 3 4 6% 52%	2280
	21st to end	Night	15% 5% 1 5% 3 3 3 3 5% 6% 51%	2508
November	1st to 10th	Night	11% 5% 2 5% 3 3 3 3 5% 6% 54%	2412
	11th to 20th	Night	14% 7% 2 5% 3 3 3 4 6% 7% 47%	2670
	21st to end	Night	14% 4 2 6% 4 4 4 4 6% 8% 45%	2800
December	1st to 10th	Night	10% 5% 2 5% 4 4 4 4 6% 8% 49%	4580
	11th to 20th	Night	19% 7% 2 5% 4 4 5% 4 5% 7% 38%	5205
	21st to end	Night	16% 7% 2 7% 5% 5% 5% 5% 7% 8% 32%	6996

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	36% 6% 7% 27% 18% 6%	3762
	11th to 20th	Day	41% 4 8% 20% 19% 7%	4060
	21st to end	Day	41% 5% 11% 25% 14% 3	4466
February	1st to 10th	Day	44% 6% 13% 23% 11% 2	1800
	11th to 20th	Day	46% 5% 9% 24% 14% 2	1779
	21st to end	Day	46% 6% 11% 20% 15% 3	1570
March	1st to 10th	Day	48% 6% 10% 21% 12% 2	3430
	11th to 20th	Day	33% 7% 10% 29% 19% 3	3480
	21st to end	Day	45% 6% 11% 21% 15% 3	3838
April	1st to 10th	Day	40% 7% 13% 19% 17% 4	2280
	11th to 20th	Day	36% 7% 11% 22% 18% 5%	2254
	21st to end	Day	43% 6% 9% 22% 16% 4	2289
May	1st to 10th	Day	50% 8% 10% 21% 10% 1	4120
	11th to 20th	Day	48% 9% 13% 21% 8% 2	4238
	21st to end	Day	33% 9% 15% 25% 17% 2	4837
June	1st to 10th	Day	35% 8% 15% 25% 16% 1	2660
	11th to 20th	Day	37% 9% 15% 23% 14% 2	2660
	21st to end	Day	32% 8% 16% 26% 16% 2	2660
July	1st to 10th	Day	34% 9% 17% 24% 11% 5%	4370
	11th to 20th	Day	34% 8% 15% 28% 12% 1	4177
	21st to end	Day	42% 7% 10% 21% 18% 1	4324
August	1st to 10th	Day	45% 8% 14% 24% 8% 1	4091
	11th to 20th	Day	36% 7% 13% 28% 15% 1	3969
	21st to end	Day	33% 7% 14% 27% 18% 2	4180
September	1st to 10th	Day	38% 6% 12% 20% 21% 4	2280
	11th to 20th	Day	35% 6% 10% 25% 22% 3	2275
	21st to end	Day	46% 5% 10% 19% 18% 2	1985
October	1st to 10th	Day	37% 5% 7% 20% 28% 5%	3160
	11th to 20th	Day	26% 5% 9% 28% 24% 8%	3140
	21st to end	Day	24% 3 11% 30% 28% 4	3428
November	1st to 10th	Day	32% 4 13% 26% 20% 4	1883
	11th to 20th	Day	36% 4 11% 24% 21% 4	1728
	21st to end	Day	38% 6% 12% 28% 14% 2	1600
December	1st to 10th	Day	38% 5% 13% 29% 12% 4	2600
	11th to 20th	Day	45% 4 13% 26% 10% 2	2986
	21st to end	Day	45% 7% 16% 18% 13% 1	3960
January	1st to 10th	Night	34% 6% 8% 26% 23% 4	6169
	11th to 20th	Night	37% 4 10% 25% 19% 6%	5900
	21st to end	Night	38% 4 9% 30% 17% 2	6490
February	1st to 10th	Night	42% 5% 14% 24% 13% 1	2600
	11th to 20th	Night	44% 5% 9% 23% 15% 4	2516
	21st to end	Night	45% 5% 11% 21% 13% 5%	1885
March	1st to 10th	Night	46% 5% 10% 26% 11% 1	3420
	11th to 20th	Night	33% 7% 10% 32% 16% 2	3480
	21st to end	Night	40% 4 8% 24% 19% 4	3793
April	1st to 10th	Night	43% 7% 10% 20% 17% 4	1900
	11th to 20th	Night	38% 6% 12% 21% 18% 6%	1875
	21st to end	Night	38% 7% 12% 26% 13% 4	1900
May	1st to 10th	Night	53% 6% 10% 19% 10% 3	2847
	11th to 20th	Night	51% 8% 11% 20% 9% 1	2659
	21st to end	Night	33% 10% 18% 25% 11% 2	2739
June	1st to 10th	Night	34% 8% 13% 26% 17% 3	1520
	11th to 20th	Night	37% 9% 13% 25% 14% 2	1520
	21st to end	Night	33% 7% 15% 25% 18% 3	1520
July	1st to 10th	Night	37% 9% 19% 18% 12% 5%	2480
	11th to 20th	Night	37% 9% 17% 21% 14% 1	2655
	21st to end	Night	39% 9% 14% 20% 17% 1	2988
August	1st to 10th	Night	46% 7% 16% 22% 8% 1	2814
	11th to 20th	Night	40% 7% 12% 26% 14% 1	2894
	21st to end	Night	34% 6% 13% 29% 16% 2	3476
September	1st to 10th	Night	37% 7% 12% 21% 18% 5%	1900
	11th to 20th	Night	34% 5% 10% 27% 23% 3	1901
	21st to end	Night	46% 5% 9% 20% 17% 2	2194
October	1st to 10th	Night	41% 4 9% 22% 21% 3	3800
	11th to 20th	Night	24% 4 10% 23% 31% 7%	3779
	21st to end	Night	23% 4 10% 32% 26% 5%	4120
November	1st to 10th	Night	31% 4 11% 27% 22% 5%	2412
	11th to 20th	Night	35% 5% 9% 25% 21% 5%	2670
	21st to end	Night	36% 6% 12% 24% 18% 3	2800
December	1st to 10th	Night	33% 6% 13% 30% 17% 1	4580
	11th to 20th	Night	45% 5% 13% 20% 15% 3	5208
	21st to end	Night	45% 8% 14% 19% 13% 1	6996

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	28% 30% 27% 11% 3 1	237
	11th to 20th	Day	34% 25% 27% 11% 3	300
	21st to end	Day	27% 29% 30% 10% 3 1	330
February	1st to 10th	Day	26% 30% 31% 10% 3	300
	11th to 20th	Day	37% 28% 28% 5% 1	317
	21st to end	Day	31% 21% 28% 16% 3	382
March	1st to 10th	Day	24% 24% 29% 20% 3	460
	11th to 20th	Day	27% 23% 30% 15% 4 2	460
	21st to end	Day	23% 22% 31% 18% 5% 1	506
April	1st to 10th	Day	22% 26% 25% 20% 6% 2	460
	11th to 20th	Day	18% 19% 29% 19% 12% 3	452
	21st to end	Day	28% 17% 27% 18% 8% 2	460
May	1st to 10th	Day	23% 19% 26% 19% 10% 3	463
	11th to 20th	Day	21% 13% 25% 24% 13% 4	487
	21st to end	Day	17% 7% 26% 25% 19% 6%	529
June	1st to 10th	Day	14% 11% 28% 22% 19% 6%	490
	11th to 20th	Day	12% 7% 29% 30% 18% 5%	490
	21st to end	Day	10% 7% 28% 32% 17% 6%	490
July	1st to 10th	Day	10% 5% 20% 28% 26% 12%	485
	11th to 20th	Day	7% 2 21% 32% 29% 8%	484
	21st to end	Day	13% 6% 20% 32% 21% 8%	532
August	1st to 10th	Day	12% 5% 20% 27% 24% 13%	486
	11th to 20th	Day	13% 3 23% 30% 20% 11%	479
	21st to end	Day	9% 5% 21% 30% 20% 14%	539
September	1st to 10th	Day	18% 7% 19% 22% 23% 10%	490
	11th to 20th	Day	14% 4 19% 32% 19% 11%	490
	21st to end	Day	27% 9% 23% 25% 12% 4	490
October	1st to 10th	Day	19% 8% 20% 26% 20% 6%	490
	11th to 20th	Day	16% 15% 26% 27% 13% 3	490
	21st to end	Day	15% 14% 33% 22% 13% 3	539
November	1st to 10th	Day	16% 13% 32% 25% 12% 3	458
	11th to 20th	Day	21% 18% 32% 19% 9% 1	328
	21st to end	Day	23% 23% 30% 20% 5% 1	200
December	1st to 10th	Day	22% 25% 36% 14% 4 1	200
	11th to 20th	Day	26% 23% 28% 18% 6% 1	200
	21st to end	Day	22% 22% 29% 19% 7%	220
January	1st to 10th	Night	20% 22% 38% 18% 3	800
	11th to 20th	Night	23% 17% 31% 25% 3	800
	21st to end	Night	19% 19% 39% 22% 2	880
February	1st to 10th	Night	17% 19% 35% 26% 3	800
	11th to 20th	Night	24% 24% 33% 17% 1	783
	21st to end	Night	24% 20% 36% 17% 3	629
March	1st to 10th	Night	21% 17% 37% 22% 3	760
	11th to 20th	Night	25% 18% 29% 22% 5% 1	760
	21st to end	Night	20% 18% 36% 22% 4 1	836
April	1st to 10th	Night	20% 20% 33% 23% 5%	760
	11th to 20th	Night	16% 14% 35% 28% 7% 1	751
	21st to end	Night	19% 13% 32% 28% 7%	760
May	1st to 10th	Night	21% 8% 29% 32% 10% 1	577
	11th to 20th	Night	20% 8% 25% 35% 11% 1	472
	21st to end	Night	14% 4 24% 38% 17% 1	411
June	1st to 10th	Night	12% 4 25% 35% 23% 1	380
	11th to 20th	Night	12% 5% 19% 43% 19% 2	380
	21st to end	Night	10% 3 23% 45% 18% 1	380
July	1st to 10th	Night	10% 5% 17% 39% 26% 3	370
	11th to 20th	Night	7% 2 12% 43% 33% 3	473
	21st to end	Night	8% 2 18% 41% 28% 3	624
August	1st to 10th	Night	11% 2 12% 44% 29% 3	567
	11th to 20th	Night	10% 4 16% 38% 29% 3	607
	21st to end	Night	14% 3 16% 39% 25% 4	836
September	1st to 10th	Night	16% 2 20% 34% 25% 3	760
	11th to 20th	Night	13% 3 17% 36% 27% 3	760
	21st to end	Night	23% 4 21% 31% 21% 1	760
October	1st to 10th	Night	22% 7% 21% 28% 20% 3	760
	11th to 20th	Night	15% 12% 27% 31% 13% 1	760
	21st to end	Night	19% 10% 31% 29% 11%	836
November	1st to 10th	Night	12% 10% 35% 33% 10% 1	780
	11th to 20th	Night	18% 14% 33% 27% 7% 1	800
	21st to end	Night	17% 16% 32% 28% 7%	800
December	1st to 10th	Night	21% 15% 34% 23% 6%	800
	11th to 20th	Night	19% 13% 38% 26% 4	800
	21st to end	Night	20% 14% 33% 30% 3	880

Page generated at 2025-02-18 03:26:33. Version ac07

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