Salt Fork State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Salt Fork State Park clear sky chart from 2005-11-06 to 2026-04-17.

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% 10% 4 8% 5% 5% 5% 4 5% 7% 32%	131097
	Night	16% 12% 4 9% 5% 4 4 3 5% 6% 32%	131026
Transparency	Day	50% 6% 10% 21% 12% 1	134741
	Night	51% 5% 10% 20% 12% 2	135452
Seeing	Day	24% 13% 27% 20% 11% 4	16571
	Night	22% 11% 26% 27% 13% 2	26831

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	18% 19% 6% 18% 4 4 3 3 4 5% 17%	5258
	11th to 20th	Day	13% 20% 8% 15% 8% 5% 4 2 3 4 17%	5280
	21st to end	Day	19% 17% 6% 12% 9% 6% 5% 3 4 4 16%	5780
February	1st to 10th	Day	19% 16% 6% 10% 6% 4 4 3 4 4 25%	1890
	11th to 20th	Day	17% 15% 6% 12% 5% 4 3 3 5% 5% 25%	1927
	21st to end	Day	18% 15% 4 9% 5% 4 3 3 3 5% 31%	1730
March	1st to 10th	Day	18% 15% 5% 9% 5% 4 4 3 4 5% 29%	4955
	11th to 20th	Day	12% 9% 3 8% 5% 4 4 4 5% 6% 39%	5090
	21st to end	Day	20% 9% 3 9% 5% 5% 4 3 5% 6% 31%	5586
April	1st to 10th	Day	16% 12% 3 7% 6% 5% 4 4 5% 7% 32%	2339
	11th to 20th	Day	16% 9% 3 8% 5% 5% 5% 3 5% 7% 35%	2585
	21st to end	Day	18% 8% 2 7% 5% 5% 4 4 6% 8% 33%	2600
May	1st to 10th	Day	21% 9% 3 8% 5% 5% 6% 4 6% 6% 27%	5862
	11th to 20th	Day	19% 9% 3 7% 5% 5% 5% 4 6% 8% 31%	5861
	21st to end	Day	17% 7% 2 7% 5% 5% 5% 5% 6% 8% 32%	6433
June	1st to 10th	Day	12% 8% 2 6% 5% 5% 5% 6% 6% 8% 37%	2617
	11th to 20th	Day	12% 6% 3 8% 5% 5% 6% 5% 7% 8% 35%	2750
	21st to end	Day	11% 6% 2 6% 6% 5% 6% 5% 8% 9% 37%	2600
July	1st to 10th	Day	10% 7% 2 6% 5% 4 5% 3 6% 9% 41%	5900
	11th to 20th	Day	11% 7% 2 7% 5% 5% 6% 5% 7% 9% 35%	5900
	21st to end	Day	11% 8% 3 7% 5% 5% 5% 4 7% 9% 35%	6424
August	1st to 10th	Day	11% 6% 3 7% 6% 6% 6% 6% 7% 9% 34%	4234
	11th to 20th	Day	10% 7% 2 6% 5% 5% 6% 5% 8% 9% 37%	4174
	21st to end	Day	7% 4 2 6% 5% 5% 5% 4 7% 10% 45%	4558
September	1st to 10th	Day	14% 6% 2 5% 4 3 4 3 5% 8% 48%	2278
	11th to 20th	Day	8% 5% 2 5% 4 5% 5% 3 6% 10% 47%	2200
	21st to end	Day	19% 9% 2 6% 5% 4 4 3 5% 7% 37%	2200
October	1st to 10th	Day	13% 7% 3 5% 5% 4 4 3 6% 7% 44%	2070
	11th to 20th	Day	16% 8% 2 7% 4 5% 5% 4 5% 5% 39%	2000
	21st to end	Day	21% 9% 3 6% 4 4 4 2 4 5% 36%	2200
November	1st to 10th	Day	12% 8% 3 7% 4 4 4 4 4 5% 46%	1886
	11th to 20th	Day	18% 13% 3 7% 5% 4 4 3 6% 6% 32%	1890
	21st to end	Day	18% 15% 6% 9% 5% 4 4 4 4 5% 27%	1749
December	1st to 10th	Day	19% 13% 5% 14% 5% 4 4 3 4 5% 24%	2680
	11th to 20th	Day	23% 17% 6% 9% 5% 3 3 3 4 5% 22%	3070
	21st to end	Day	22% 21% 5% 11% 6% 5% 4 2 3 4 15%	4541
January	1st to 10th	Night	17% 18% 8% 17% 6% 5% 4 3 4 4 15%	7635
	11th to 20th	Night	13% 19% 7% 15% 8% 6% 5% 3 4 4 16%	7680
	21st to end	Night	19% 16% 5% 11% 6% 6% 4 3 4 5% 23%	8401
February	1st to 10th	Night	19% 15% 5% 9% 6% 4 4 3 4 4 26%	2730
	11th to 20th	Night	19% 14% 6% 10% 6% 5% 4 3 4 4 24%	2574
	21st to end	Night	19% 16% 4 10% 6% 4 4 2 4 4 26%	2076
March	1st to 10th	Night	21% 13% 4 7% 4 4 3 2 4 5% 33%	5118
	11th to 20th	Night	13% 10% 4 6% 4 4 4 3 6% 8% 38%	5090
	21st to end	Night	19% 9% 3 8% 5% 4 4 3 4 6% 35%	5588
April	1st to 10th	Night	19% 12% 3 7% 4 4 4 3 5% 6% 33%	2279
	11th to 20th	Night	15% 8% 3 7% 5% 4 4 5% 6% 8% 35%	1913
	21st to end	Night	15% 9% 3 7% 4 4 5% 4 5% 8% 38%	1800
May	1st to 10th	Night	27% 10% 3 7% 5% 5% 4 4 5% 6% 25%	4033
	11th to 20th	Night	17% 9% 3 6% 4 4 4 3 5% 9% 37%	4032
	21st to end	Night	16% 7% 3 6% 5% 5% 5% 4 6% 8% 35%	4421
June	1st to 10th	Night	9% 6% 2 7% 5% 5% 4 4 6% 8% 45%	1764
	11th to 20th	Night	11% 6% 2 6% 4 4 4 4 7% 11% 42%	1628
	21st to end	Night	11% 5% 2 5% 5% 5% 4 4 6% 10% 44%	1800
July	1st to 10th	Night	10% 7% 3 7% 4 4 4 4 6% 8% 42%	4058
	11th to 20th	Night	11% 6% 2 7% 5% 5% 5% 4 7% 9% 37%	4057
	21st to end	Night	8% 7% 3 7% 5% 5% 5% 4 7% 8% 40%	4427
August	1st to 10th	Night	8% 8% 3 9% 5% 4 6% 5% 8% 9% 36%	2915
	11th to 20th	Night	13% 8% 2 7% 4 4 4 3 5% 6% 44%	2875
	21st to end	Night	6% 5% 2 5% 5% 5% 6% 5% 7% 9% 46%	3305
September	1st to 10th	Night	11% 5% 2 6% 4 4 4 3 4 6% 51%	2119
	11th to 20th	Night	9% 4 1 4 3 4 4 3 6% 9% 54%	2200
	21st to end	Night	16% 7% 3 7% 4 4 4 3 5% 6% 43%	2200
October	1st to 10th	Night	13% 5% 2 6% 4 3 4 4 5% 6% 48%	2328
	11th to 20th	Night	15% 7% 3 7% 5% 5% 4 4 4 7% 41%	2400
	21st to end	Night	22% 8% 2 5% 4 4 4 3 5% 7% 37%	2640
November	1st to 10th	Night	13% 8% 2 6% 4 4 3 3 4 7% 46%	2629
	11th to 20th	Night	18% 11% 3 7% 4 4 4 4 5% 6% 34%	2730
	21st to end	Night	21% 13% 4 7% 4 4 5% 4 5% 6% 28%	2865
December	1st to 10th	Night	19% 13% 7% 13% 5% 5% 4 3 4 5% 22%	4720
	11th to 20th	Night	19% 20% 7% 10% 4 3 3 2 4 5% 22%	5345
	21st to end	Night	23% 19% 5% 9% 5% 5% 4 3 4 5% 18%	6651

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	70% 5% 11% 11% 4	5259
	11th to 20th	Day	72% 4 7% 9% 8% 1	5280
	21st to end	Day	72% 4 7% 12% 5%	5780
February	1st to 10th	Day	63% 4 9% 15% 8% 1	1890
	11th to 20th	Day	61% 4 8% 17% 8% 1	1936
	21st to end	Day	59% 2 10% 19% 8% 2	1730
March	1st to 10th	Day	57% 4 7% 22% 8% 1	4955
	11th to 20th	Day	43% 6% 9% 29% 10% 2	5090
	21st to end	Day	52% 5% 8% 20% 13% 1	5586
April	1st to 10th	Day	52% 5% 10% 19% 11% 2	2339
	11th to 20th	Day	48% 6% 12% 17% 15% 2	2585
	21st to end	Day	49% 6% 9% 21% 13% 2	2600
May	1st to 10th	Day	55% 8% 8% 17% 9% 3	5897
	11th to 20th	Day	50% 7% 10% 21% 11% 1	5865
	21st to end	Day	46% 8% 12% 21% 11% 3	6447
June	1st to 10th	Day	43% 7% 11% 24% 14% 1	2617
	11th to 20th	Day	44% 7% 13% 23% 12% 1	2750
	21st to end	Day	41% 8% 14% 23% 14% 2	2600
July	1st to 10th	Day	38% 6% 12% 27% 15% 2	5835
	11th to 20th	Day	42% 9% 12% 24% 12%	5831
	21st to end	Day	41% 8% 11% 20% 18% 2	6240
August	1st to 10th	Day	42% 8% 14% 24% 11%	4221
	11th to 20th	Day	38% 8% 10% 31% 12% 1	4213
	21st to end	Day	32% 8% 13% 32% 13% 2	4558
September	1st to 10th	Day	36% 4 11% 23% 21% 4	2278
	11th to 20th	Day	33% 4 14% 28% 19% 3	2200
	21st to end	Day	47% 5% 9% 21% 17% 1	2200
October	1st to 10th	Day	28% 5% 9% 34% 22% 1	3369
	11th to 20th	Day	41% 6% 11% 22% 16% 4	3240
	21st to end	Day	38% 4 12% 26% 19% 1	3538
November	1st to 10th	Day	40% 4 9% 28% 16% 3	1886
	11th to 20th	Day	53% 4 8% 22% 10% 3	1890
	21st to end	Day	59% 5% 9% 18% 8% 1	1749
December	1st to 10th	Day	63% 5% 14% 15% 4	2680
	11th to 20th	Day	67% 3 10% 15% 5%	3066
	21st to end	Day	73% 5% 8% 10% 5%	4541
January	1st to 10th	Night	73% 4 8% 11% 3	7636
	11th to 20th	Night	71% 4 8% 11% 5%	7680
	21st to end	Night	64% 4 10% 15% 6% 1	8401
February	1st to 10th	Night	61% 5% 9% 17% 7% 1	2730
	11th to 20th	Night	63% 4 8% 16% 8%	2576
	21st to end	Night	62% 4 8% 15% 8% 2	2076
March	1st to 10th	Night	54% 4 7% 24% 10% 1	5118
	11th to 20th	Night	43% 6% 10% 29% 9% 2	5090
	21st to end	Night	50% 5% 8% 22% 14% 2	5588
April	1st to 10th	Night	52% 5% 9% 19% 13% 2	2279
	11th to 20th	Night	45% 5% 12% 18% 17% 3	1913
	21st to end	Night	45% 5% 10% 22% 16% 2	1800
May	1st to 10th	Night	59% 6% 9% 14% 7% 4	4060
	11th to 20th	Night	45% 7% 10% 25% 13% 1	4033
	21st to end	Night	44% 7% 13% 23% 10% 3	4429
June	1st to 10th	Night	37% 6% 11% 25% 18% 3	1764
	11th to 20th	Night	35% 7% 15% 23% 18% 2	1628
	21st to end	Night	36% 8% 12% 24% 18% 2	1800
July	1st to 10th	Night	39% 6% 10% 23% 18% 3	4015
	11th to 20th	Night	39% 10% 16% 22% 12% 1	4006
	21st to end	Night	38% 8% 11% 20% 20% 3	4297
August	1st to 10th	Night	41% 9% 14% 23% 12% 1	2904
	11th to 20th	Night	40% 6% 9% 24% 20% 1	2902
	21st to end	Night	30% 8% 14% 29% 15% 2	3305
September	1st to 10th	Night	35% 5% 11% 22% 22% 6%	2119
	11th to 20th	Night	28% 5% 12% 27% 25% 2	2200
	21st to end	Night	43% 4 10% 21% 21% 1	2200
October	1st to 10th	Night	31% 4 7% 28% 28% 2	3809
	11th to 20th	Night	35% 6% 11% 24% 18% 7%	3899
	21st to end	Night	34% 4 8% 28% 23% 3	4252
November	1st to 10th	Night	38% 4 11% 25% 18% 3	2629
	11th to 20th	Night	51% 4 9% 21% 13% 2	2730
	21st to end	Night	58% 4 10% 20% 7% 1	2865
December	1st to 10th	Night	64% 5% 11% 17% 4	4720
	11th to 20th	Night	65% 4 13% 14% 3	5348
	21st to end	Night	69% 5% 9% 13% 4	6651

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	35% 21% 30% 10% 4	330
	11th to 20th	Day	39% 27% 27% 6% 1	330
	21st to end	Day	36% 25% 29% 9% 1	363
February	1st to 10th	Day	33% 22% 33% 9% 3	330
	11th to 20th	Day	41% 22% 30% 5% 1	330
	21st to end	Day	35% 23% 36% 5%	273
March	1st to 10th	Day	32% 21% 30% 13% 4	498
	11th to 20th	Day	33% 19% 30% 12% 5% 1	540
	21st to end	Day	33% 18% 31% 15% 3	594
April	1st to 10th	Day	29% 18% 32% 14% 6% 1	540
	11th to 20th	Day	27% 18% 29% 16% 7% 3	516
	21st to end	Day	27% 16% 35% 14% 6% 2	500
May	1st to 10th	Day	29% 15% 29% 17% 8% 2	503
	11th to 20th	Day	22% 11% 32% 21% 8% 5%	527
	21st to end	Day	18% 9% 25% 27% 16% 6%	573
June	1st to 10th	Day	18% 7% 28% 29% 13% 5%	530
	11th to 20th	Day	18% 8% 25% 31% 13% 5%	530
	21st to end	Day	12% 7% 31% 28% 16% 5%	530
July	1st to 10th	Day	17% 4 20% 26% 20% 13%	525
	11th to 20th	Day	14% 5% 23% 29% 20% 8%	524
	21st to end	Day	14% 6% 21% 28% 18% 12%	576
August	1st to 10th	Day	12% 4 20% 33% 21% 9%	526
	11th to 20th	Day	16% 5% 18% 32% 20% 9%	519
	21st to end	Day	10% 4 22% 30% 24% 9%	583
September	1st to 10th	Day	16% 6% 20% 27% 21% 10%	530
	11th to 20th	Day	11% 4 15% 29% 30% 12%	530
	21st to end	Day	25% 8% 24% 24% 15% 5%	530
October	1st to 10th	Day	15% 8% 25% 27% 20% 4	530
	11th to 20th	Day	20% 13% 31% 23% 12% 2	530
	21st to end	Day	28% 14% 31% 18% 8% 1	583
November	1st to 10th	Day	21% 15% 37% 14% 9% 2	364
	11th to 20th	Day	32% 16% 30% 16% 5% 2	330
	21st to end	Day	29% 22% 35% 12% 2	256
December	1st to 10th	Day	32% 22% 32% 9% 4 2	220
	11th to 20th	Day	34% 24% 28% 12% 3	220
	21st to end	Day	39% 19% 31% 9% 2	358
January	1st to 10th	Night	31% 18% 32% 15% 4	840
	11th to 20th	Night	31% 20% 31% 15% 3	840
	21st to end	Night	31% 20% 29% 18% 2	924
February	1st to 10th	Night	30% 17% 30% 21% 3	840
	11th to 20th	Night	30% 20% 32% 17% 1	823
	21st to end	Night	29% 18% 35% 16% 2	692
March	1st to 10th	Night	27% 16% 30% 23% 4	840
	11th to 20th	Night	28% 17% 27% 22% 5% 1	840
	21st to end	Night	29% 15% 32% 19% 5% 1	924
April	1st to 10th	Night	26% 15% 31% 22% 5%	840
	11th to 20th	Night	19% 14% 36% 21% 8% 1	693
	21st to end	Night	20% 9% 35% 28% 7% 1	600
May	1st to 10th	Night	22% 9% 27% 28% 12% 1	600
	11th to 20th	Night	21% 7% 24% 33% 14% 1	591
	21st to end	Night	12% 4 21% 36% 24% 3	650
June	1st to 10th	Night	11% 5% 25% 37% 21% 1	564
	11th to 20th	Night	14% 5% 22% 36% 22% 1	428
	21st to end	Night	13% 3 21% 38% 24% 3	600
July	1st to 10th	Night	10% 3 15% 41% 26% 6%	585
	11th to 20th	Night	10% 2 17% 37% 29% 5%	582
	21st to end	Night	10% 2 13% 40% 31% 4	657
August	1st to 10th	Night	8% 3 14% 41% 31% 3	597
	11th to 20th	Night	11% 3 12% 37% 32% 6%	594
	21st to end	Night	10% 2 18% 33% 32% 6%	703
September	1st to 10th	Night	14% 3 17% 33% 29% 4	800
	11th to 20th	Night	10% 3 13% 37% 32% 5%	800
	21st to end	Night	19% 7% 20% 32% 19% 4	800
October	1st to 10th	Night	16% 5% 19% 33% 23% 3	800
	11th to 20th	Night	20% 10% 28% 29% 12% 1	800
	21st to end	Night	27% 11% 27% 26% 8% 1	880
November	1st to 10th	Night	19% 9% 30% 30% 12%	820
	11th to 20th	Night	26% 14% 29% 21% 8% 1	840
	21st to end	Night	31% 13% 27% 24% 5%	840
December	1st to 10th	Night	33% 15% 28% 19% 5%	840
	11th to 20th	Night	30% 16% 29% 21% 4	840
	21st to end	Night	34% 13% 30% 21% 2	924

Page generated at 2026-04-14 02:44:26. Version ac07

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