Echo Bluff State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Echo Bluff State Park clear sky chart from 2005-11-06 to 2025-01-07.

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	13% 7% 2 6% 4 4 4 4 5% 7% 44%	104738
	Night	14% 7% 2 6% 4 3 4 3 5% 6% 46%	104379
Transparency	Day	37% 7% 11% 24% 17% 3	108375
	Night	36% 6% 11% 24% 18% 4	108884
Seeing	Day	17% 12% 26% 25% 15% 4	15731
	Night	18% 11% 28% 27% 14% 2	25627

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% 11% 4 7% 3 4 3 3 4 5% 43%	2703
	11th to 20th	Day	13% 9% 3 7% 4 4 4 3 4 5% 45%	2850
	21st to end	Day	25% 7% 3 6% 3 2 3 3 3 5% 40%	3135
February	1st to 10th	Day	17% 10% 3 7% 5% 4 4 4 4 5% 38%	1710
	11th to 20th	Day	17% 8% 3 6% 4 3 4 4 5% 6% 41%	1799
	21st to end	Day	17% 10% 3 5% 4 4 4 4 5% 6% 38%	1570
March	1st to 10th	Day	20% 12% 2 6% 3 3 3 3 4 4 40%	3312
	11th to 20th	Day	14% 7% 2 5% 3 3 3 3 4 6% 52%	3480
	21st to end	Day	16% 7% 2 7% 4 5% 5% 4 5% 6% 38%	3931
April	1st to 10th	Day	12% 7% 3 7% 4 3 3 4 5% 7% 46%	2280
	11th to 20th	Day	17% 8% 3 6% 4 4 4 3 5% 6% 40%	2254
	21st to end	Day	18% 8% 3 6% 6% 4 4 4 5% 5% 37%	2280
May	1st to 10th	Day	15% 7% 3 7% 6% 5% 6% 5% 7% 9% 32%	3765
	11th to 20th	Day	16% 7% 2 7% 4 4 4 4 5% 7% 39%	4251
	21st to end	Day	14% 7% 2 6% 5% 5% 4 3 5% 9% 40%	4824
June	1st to 10th	Day	9% 5% 2 7% 6% 6% 5% 4 6% 8% 43%	2660
	11th to 20th	Day	6% 4 2 5% 5% 5% 5% 4 7% 9% 50%	2660
	21st to end	Day	5% 3 2 4 5% 5% 6% 5% 8% 9% 49%	2660
July	1st to 10th	Day	11% 4 2 7% 5% 4 5% 4 6% 9% 42%	4440
	11th to 20th	Day	4 4 2 5% 4 5% 5% 5% 7% 11% 49%	4233
	21st to end	Day	8% 6% 3 7% 6% 6% 7% 6% 7% 10% 35%	4465
August	1st to 10th	Day	4 3 2 4 4 4 5% 4 6% 9% 55%	4104
	11th to 20th	Day	12% 5% 2 6% 5% 5% 5% 4 6% 7% 43%	3742
	21st to end	Day	7% 4 1 5% 3 4 4 4 6% 8% 53%	4180
September	1st to 10th	Day	11% 5% 1 5% 3 4 5% 4 6% 7% 49%	2280
	11th to 20th	Day	11% 5% 2 6% 4 4 4 4 6% 7% 47%	2280
	21st to end	Day	10% 5% 2 5% 4 3 4 3 5% 7% 52%	2029
October	1st to 10th	Day	9% 5% 2 5% 3 4 4 2 5% 5% 56%	1900
	11th to 20th	Day	14% 6% 2 4 3 3 2 2 3 5% 55%	1900
	21st to end	Day	19% 6% 3 5% 3 3 3 3 4 5% 47%	2090
November	1st to 10th	Day	14% 6% 2 4 3 3 4 3 4 5% 53%	1853
	11th to 20th	Day	13% 7% 3 6% 3 3 3 3 4 7% 50%	1800
	21st to end	Day	19% 8% 2 5% 3 3 4 2 4 4 45%	1718
December	1st to 10th	Day	12% 9% 2 5% 3 3 4 2 4 5% 50%	2610
	11th to 20th	Day	14% 10% 3 8% 4 4 4 2 4 5% 42%	3008
	21st to end	Day	20% 19% 4 7% 4 4 4 3 4 4 29%	3982
January	1st to 10th	Night	16% 9% 5% 7% 4 4 4 3 5% 5% 39%	4380
	11th to 20th	Night	14% 8% 3 9% 5% 4 4 3 4 6% 41%	4120
	21st to end	Night	23% 11% 3 6% 3 3 3 2 4 4 37%	4532
February	1st to 10th	Night	16% 10% 3 7% 3 3 3 3 5% 6% 41%	2470
	11th to 20th	Night	15% 7% 3 7% 4 3 3 3 4 7% 44%	2266
	21st to end	Night	18% 9% 2 6% 4 3 4 4 4 5% 42%	1884
March	1st to 10th	Night	22% 10% 2 5% 3 2 3 3 3 5% 43%	3555
	11th to 20th	Night	14% 7% 2 5% 4 3 3 3 4 6% 49%	3480
	21st to end	Night	15% 10% 3 7% 4 4 4 3 6% 7% 37%	3699
April	1st to 10th	Night	10% 6% 2 4 4 4 3 3 5% 8% 51%	1900
	11th to 20th	Night	13% 7% 2 6% 4 4 3 3 5% 7% 45%	1875
	21st to end	Night	18% 7% 2 6% 4 3 4 3 5% 8% 41%	1900
May	1st to 10th	Night	18% 5% 2 4 3 3 4 4 6% 8% 43%	3130
	11th to 20th	Night	14% 8% 2 6% 3 3 3 4 5% 9% 42%	2649
	21st to end	Night	13% 9% 2 7% 5% 5% 4 3 6% 8% 39%	2743
June	1st to 10th	Night	8% 4 2 5% 5% 4 3 4 6% 8% 50%	1520
	11th to 20th	Night	5% 3 1 3 2 3 3 4 6% 11% 59%	1520
	21st to end	Night	3 3 1 3 3 4 3 4 7% 11% 59%	1520
July	1st to 10th	Night	10% 4 2 5% 4 4 5% 4 6% 10% 47%	2530
	11th to 20th	Night	4 3 1 4 3 3 3 3 6% 8% 62%	2719
	21st to end	Night	8% 5% 3 8% 5% 5% 6% 5% 7% 7% 42%	3098
August	1st to 10th	Night	3 2 1 4 3 3 4 4 6% 8% 61%	2836
	11th to 20th	Night	9% 5% 2 5% 5% 5% 5% 3 5% 7% 49%	3085
	21st to end	Night	5% 4 2 4 3 3 4 3 5% 9% 59%	3476
September	1st to 10th	Night	10% 4 2 4 3 3 4 3 5% 7% 54%	1900
	11th to 20th	Night	10% 5% 2 4 4 4 4 4 5% 7% 53%	1900
	21st to end	Night	8% 5% 2 6% 3 3 4 3 5% 6% 54%	2127
October	1st to 10th	Night	7% 4 1 4 2 3 3 3 4 6% 62%	2280
	11th to 20th	Night	13% 6% 1 4 3 3 2 2 5% 5% 56%	2280
	21st to end	Night	19% 6% 2 4 3 3 4 2 3 5% 49%	2508
November	1st to 10th	Night	12% 5% 2 5% 2 2 3 2 5% 5% 56%	2442
	11th to 20th	Night	14% 6% 2 5% 4 3 3 3 4 6% 50%	2600
	21st to end	Night	18% 9% 2 5% 3 3 3 2 3 5% 46%	2680
December	1st to 10th	Night	13% 8% 2 5% 3 3 4 2 5% 6% 49%	4580
	11th to 20th	Night	18% 9% 2 6% 4 4 3 2 4 5% 44%	5199
	21st to end	Night	26% 15% 4 7% 4 4 3 3 4 4 27%	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	43% 4 9% 27% 14% 2	2704
	11th to 20th	Day	42% 5% 10% 24% 16% 4	2850
	21st to end	Day	48% 4 9% 17% 17% 6%	3135
February	1st to 10th	Day	49% 4 11% 21% 13% 1	1710
	11th to 20th	Day	44% 5% 11% 21% 15% 5%	1809
	21st to end	Day	47% 5% 8% 21% 12% 7%	1570
March	1st to 10th	Day	47% 6% 7% 20% 12% 9%	3312
	11th to 20th	Day	34% 5% 10% 27% 17% 7%	3480
	21st to end	Day	42% 8% 16% 20% 13% 1	3931
April	1st to 10th	Day	37% 5% 13% 23% 20% 2	2280
	11th to 20th	Day	45% 5% 11% 20% 16% 4	2254
	21st to end	Day	47% 7% 10% 20% 14% 1	2280
May	1st to 10th	Day	43% 11% 13% 20% 11% 1	3800
	11th to 20th	Day	42% 9% 12% 24% 12% 1	4255
	21st to end	Day	40% 10% 11% 22% 17% 1	4837
June	1st to 10th	Day	37% 9% 13% 23% 16% 1	2660
	11th to 20th	Day	29% 8% 13% 29% 18% 3	2660
	21st to end	Day	26% 9% 20% 25% 15% 5%	2660
July	1st to 10th	Day	37% 8% 13% 28% 11% 2	4371
	11th to 20th	Day	27% 8% 13% 32% 17% 3	4160
	21st to end	Day	40% 10% 16% 24% 8% 1	4325
August	1st to 10th	Day	23% 7% 17% 29% 22% 1	4090
	11th to 20th	Day	38% 7% 13% 24% 16% 2	3778
	21st to end	Day	28% 7% 15% 34% 12% 3	4179
September	1st to 10th	Day	32% 8% 12% 26% 16% 6%	2280
	11th to 20th	Day	35% 7% 9% 24% 24% 1	2280
	21st to end	Day	31% 6% 9% 26% 25% 3	2029
October	1st to 10th	Day	18% 4 5% 17% 44% 12%	3160
	11th to 20th	Day	23% 3 5% 20% 41% 8%	3140
	21st to end	Day	31% 3 6% 31% 25% 4	3428
November	1st to 10th	Day	34% 4 10% 23% 22% 6%	1853
	11th to 20th	Day	36% 4 7% 24% 22% 7%	1800
	21st to end	Day	43% 5% 8% 25% 18% 2	1718
December	1st to 10th	Day	36% 4 9% 35% 15% 1	2610
	11th to 20th	Day	45% 4 7% 24% 19% 1	3005
	21st to end	Day	58% 5% 11% 14% 10% 2	3982
January	1st to 10th	Night	44% 6% 11% 23% 15% 2	4380
	11th to 20th	Night	41% 6% 11% 26% 14% 3	4120
	21st to end	Night	49% 5% 9% 21% 14% 2	4532
February	1st to 10th	Night	45% 4 11% 23% 15% 2	2470
	11th to 20th	Night	40% 4 13% 21% 18% 3	2267
	21st to end	Night	44% 5% 8% 21% 17% 5%	1884
March	1st to 10th	Night	45% 6% 7% 22% 14% 6%	3555
	11th to 20th	Night	35% 7% 11% 24% 18% 5%	3480
	21st to end	Night	41% 9% 15% 24% 10%	3699
April	1st to 10th	Night	31% 6% 13% 24% 21% 4	1900
	11th to 20th	Night	39% 6% 11% 23% 16% 5%	1875
	21st to end	Night	42% 6% 11% 24% 15% 2	1900
May	1st to 10th	Night	36% 10% 16% 22% 14% 2	3160
	11th to 20th	Night	36% 11% 14% 22% 15% 1	2650
	21st to end	Night	41% 10% 12% 23% 13% 1	2751
June	1st to 10th	Night	30% 8% 17% 24% 19% 2	1520
	11th to 20th	Night	19% 6% 14% 36% 20% 4	1520
	21st to end	Night	18% 8% 19% 29% 18% 8%	1520
July	1st to 10th	Night	32% 7% 17% 25% 16% 3	2490
	11th to 20th	Night	20% 6% 13% 38% 20% 3	2670
	21st to end	Night	36% 10% 17% 25% 10% 1	2999
August	1st to 10th	Night	18% 7% 18% 34% 22% 1	2826
	11th to 20th	Night	33% 7% 17% 24% 16% 3	3115
	21st to end	Night	22% 6% 15% 36% 18% 3	3476
September	1st to 10th	Night	28% 6% 12% 28% 20% 5%	1900
	11th to 20th	Night	30% 7% 11% 24% 25% 2	1900
	21st to end	Night	30% 6% 10% 24% 28% 3	2127
October	1st to 10th	Night	14% 3 7% 17% 45% 15%	3800
	11th to 20th	Night	22% 3 6% 20% 35% 15%	3779
	21st to end	Night	30% 4 7% 26% 29% 4	4120
November	1st to 10th	Night	30% 4 10% 27% 23% 6%	2442
	11th to 20th	Night	35% 5% 7% 23% 23% 7%	2600
	21st to end	Night	42% 4 7% 23% 22% 2	2680
December	1st to 10th	Night	37% 4 9% 33% 17% 1	4580
	11th to 20th	Night	44% 4 8% 23% 20% 2	5201
	21st to end	Night	59% 6% 11% 16% 6% 2	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	27% 26% 31% 14% 2	288
	11th to 20th	Day	33% 25% 30% 10% 2	270
	21st to end	Day	23% 34% 31% 10% 2	297
February	1st to 10th	Day	27% 26% 33% 10% 3	270
	11th to 20th	Day	33% 24% 30% 10% 2 1	270
	21st to end	Day	33% 23% 33% 9% 1	225
March	1st to 10th	Day	27% 23% 37% 12% 1	270
	11th to 20th	Day	34% 23% 30% 11% 2	270
	21st to end	Day	31% 23% 33% 10% 3	363
April	1st to 10th	Day	23% 18% 33% 18% 6%	460
	11th to 20th	Day	25% 22% 30% 16% 7% 1	452
	21st to end	Day	23% 19% 33% 18% 5% 1	460
May	1st to 10th	Day	19% 21% 33% 20% 7% 1	463
	11th to 20th	Day	19% 12% 31% 23% 12% 4	665
	21st to end	Day	14% 9% 34% 26% 13% 4	734
June	1st to 10th	Day	10% 6% 24% 30% 23% 6%	680
	11th to 20th	Day	7% 3 22% 41% 22% 5%	680
	21st to end	Day	5% 6% 30% 36% 19% 5%	680
July	1st to 10th	Day	11% 4 16% 30% 31% 9%	671
	11th to 20th	Day	5% 3 21% 34% 29% 7%	668
	21st to end	Day	11% 3 14% 35% 29% 9%	739
August	1st to 10th	Day	9% 2 16% 39% 26% 8%	676
	11th to 20th	Day	17% 2 18% 31% 27% 6%	492
	21st to end	Day	12% 2 12% 29% 31% 14%	539
September	1st to 10th	Day	11% 4 17% 31% 29% 8%	490
	11th to 20th	Day	11% 4 17% 29% 27% 11%	490
	21st to end	Day	14% 9% 24% 27% 19% 7%	409
October	1st to 10th	Day	13% 9% 28% 33% 11% 6%	300
	11th to 20th	Day	21% 16% 34% 21% 7% 1	300
	21st to end	Day	26% 22% 29% 19% 3	330
November	1st to 10th	Day	20% 12% 35% 26% 6% 2	300
	11th to 20th	Day	21% 19% 35% 16% 8% 1	300
	21st to end	Day	31% 15% 31% 15% 6% 1	300
December	1st to 10th	Day	20% 24% 33% 16% 5% 2	300
	11th to 20th	Day	26% 22% 30% 15% 6%	300
	21st to end	Day	32% 22% 31% 12% 3	330
January	1st to 10th	Night	24% 21% 33% 19% 4	981
	11th to 20th	Night	24% 23% 33% 16% 3	950
	21st to end	Night	21% 20% 37% 21% 2	1045
February	1st to 10th	Night	24% 18% 37% 20% 1	950
	11th to 20th	Night	22% 20% 40% 17% 2	791
	21st to end	Night	25% 21% 36% 17% 1	628
March	1st to 10th	Night	24% 16% 35% 23% 3	660
	11th to 20th	Night	24% 14% 33% 24% 5%	570
	21st to end	Night	24% 17% 33% 20% 5%	627
April	1st to 10th	Night	16% 18% 37% 25% 5%	570
	11th to 20th	Night	17% 17% 32% 25% 8%	563
	21st to end	Night	21% 11% 40% 20% 7%	570
May	1st to 10th	Night	15% 9% 37% 31% 9%	570
	11th to 20th	Night	18% 7% 32% 27% 15% 2	561
	21st to end	Night	13% 6% 26% 35% 15% 4	617
June	1st to 10th	Night	9% 5% 19% 35% 31% 2	570
	11th to 20th	Night	7% 1 19% 45% 25% 2	570
	21st to end	Night	4 2 22% 39% 31% 2	570
July	1st to 10th	Night	10% 1 13% 33% 34% 9%	555
	11th to 20th	Night	5% 2 12% 40% 35% 6%	552
	21st to end	Night	5% 1 14% 39% 35% 6%	624
August	1st to 10th	Night	7% 2 10% 40% 38% 4	567
	11th to 20th	Night	9% 1 14% 38% 36% 3	564
	21st to end	Night	9% 2 10% 33% 39% 7%	627
September	1st to 10th	Night	11% 2 13% 37% 33% 4	570
	11th to 20th	Night	13% 2 14% 31% 35% 5%	570
	21st to end	Night	10% 6% 22% 30% 28% 3	719
October	1st to 10th	Night	9% 5% 25% 33% 25% 3	760
	11th to 20th	Night	17% 11% 30% 29% 12%	760
	21st to end	Night	24% 13% 28% 27% 8%	836
November	1st to 10th	Night	15% 10% 35% 30% 10% 1	780
	11th to 20th	Night	19% 14% 32% 26% 8%	800
	21st to end	Night	24% 13% 32% 24% 8%	880
December	1st to 10th	Night	23% 15% 32% 24% 5%	1000
	11th to 20th	Night	26% 14% 31% 24% 5%	1000
	21st to end	Night	29% 17% 31% 21% 3	1100

Page generated at 2025-01-04 02:23:57. Version ac07

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