Mckinney Falls State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Mckinney Falls State Park clear sky chart from 2005-11-06 to 2025-01-22.

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 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	12% 6% 2 5% 4 4 4 4 5% 7% 46%	105283
	Night	14% 6% 2 4 3 3 3 3 5% 7% 50%	104216
Transparency	Day	36% 5% 10% 21% 19% 9%	109077
	Night	34% 5% 11% 20% 20% 11%	108548
Seeing	Day	13% 5% 18% 27% 26% 10%	15081
	Night	16% 5% 23% 37% 18% 2	25112

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% 8% 2 6% 3 2 3 3 4 6% 49%	2937
	11th to 20th	Day	18% 5% 1 3 2 2 2 2 5% 6% 55%	2940
	21st to end	Day	19% 8% 2 6% 4 3 3 2 4 7% 43%	3304
February	1st to 10th	Day	21% 7% 2 5% 3 3 3 2 3 5% 44%	1900
	11th to 20th	Day	20% 8% 2 5% 3 3 3 2 4 6% 44%	1849
	21st to end	Day	19% 6% 2 6% 3 3 3 3 3 4 49%	1570
March	1st to 10th	Day	16% 7% 3 7% 5% 4 3 3 5% 6% 41%	3436
	11th to 20th	Day	21% 9% 2 7% 6% 5% 4 4 5% 5% 32%	3480
	21st to end	Day	16% 8% 2 5% 4 3 3 3 5% 6% 45%	3814
April	1st to 10th	Day	15% 8% 3 6% 4 4 4 4 5% 6% 41%	2090
	11th to 20th	Day	18% 7% 3 5% 5% 4 3 4 5% 5% 41%	2066
	21st to end	Day	14% 7% 3 6% 4 4 4 3 5% 6% 44%	2408
May	1st to 10th	Day	23% 9% 3 7% 4 4 4 3 5% 6% 30%	4082
	11th to 20th	Day	15% 7% 2 7% 4 5% 5% 4 5% 6% 42%	4082
	21st to end	Day	10% 6% 2 7% 5% 5% 6% 5% 8% 9% 35%	4477
June	1st to 10th	Day	6% 5% 2 5% 4 4 5% 4 6% 10% 48%	2470
	11th to 20th	Day	8% 5% 2 5% 4 5% 5% 5% 7% 9% 45%	2470
	21st to end	Day	6% 6% 2 6% 7% 6% 6% 5% 7% 10% 38%	2470
July	1st to 10th	Day	6% 5% 2 5% 4 5% 5% 5% 6% 9% 49%	4120
	11th to 20th	Day	4 4 2 5% 4 5% 6% 5% 7% 12% 47%	4120
	21st to end	Day	9% 7% 3 7% 5% 5% 6% 5% 7% 10% 37%	4465
August	1st to 10th	Day	1 1 1 2 2 3 3 3 5% 9% 71%	4104
	11th to 20th	Day	4 2 1 3 3 3 4 4 7% 12% 58%	3803
	21st to end	Day	4 3 1 5% 5% 6% 6% 5% 8% 11% 47%	3961
September	1st to 10th	Day	7% 6% 3 7% 5% 5% 5% 3 5% 7% 45%	2090
	11th to 20th	Day	11% 6% 2 7% 5% 5% 5% 4 7% 7% 42%	2090
	21st to end	Day	7% 5% 2 5% 3 5% 5% 4 7% 8% 49%	2090
October	1st to 10th	Day	6% 4 2 5% 3 4 4 3 5% 7% 56%	2090
	11th to 20th	Day	12% 5% 2 4 3 3 4 3 5% 6% 53%	1933
	21st to end	Day	11% 4 2 5% 2 3 3 3 3 4 59%	2090
November	1st to 10th	Day	13% 8% 2 5% 4 4 4 4 5% 5% 46%	1958
	11th to 20th	Day	12% 6% 2 5% 4 3 3 4 4 5% 51%	1905
	21st to end	Day	16% 8% 3 5% 3 3 3 3 4 5% 46%	1800
December	1st to 10th	Day	24% 8% 2 6% 3 3 3 3 4 5% 39%	2940
	11th to 20th	Day	18% 8% 3 5% 4 4 4 3 5% 5% 43%	3391
	21st to end	Day	15% 6% 2 4 2 3 3 3 3 4 56%	4488
January	1st to 10th	Night	20% 7% 2 3 2 2 2 2 3 6% 52%	4238
	11th to 20th	Night	14% 4 1 3 2 2 2 2 2 4 64%	4250
	21st to end	Night	22% 6% 2 6% 4 2 3 2 4 6% 42%	4415
February	1st to 10th	Night	19% 7% 3 5% 3 3 3 2 4 5% 46%	2280
	11th to 20th	Night	19% 7% 2 4 3 2 3 2 4 4 49%	2218
	21st to end	Night	20% 7% 2 4 3 3 4 3 4 5% 45%	1882
March	1st to 10th	Night	19% 9% 2 5% 4 5% 4 3 4 7% 39%	3419
	11th to 20th	Night	24% 10% 3 6% 4 4 4 4 5% 5% 32%	3480
	21st to end	Night	16% 7% 3 7% 4 4 4 3 5% 5% 43%	3817
April	1st to 10th	Night	15% 6% 3 5% 4 3 4 3 5% 7% 45%	2090
	11th to 20th	Night	19% 6% 2 5% 4 3 3 4 5% 6% 43%	2063
	21st to end	Night	17% 7% 2 4 4 3 3 3 4 6% 47%	1766
May	1st to 10th	Night	26% 9% 2 6% 3 3 3 3 4 5% 35%	2823
	11th to 20th	Night	13% 6% 2 5% 4 4 3 3 5% 7% 48%	2823
	21st to end	Night	14% 6% 2 4 4 3 5% 4 6% 9% 42%	3090
June	1st to 10th	Night	5% 3 1 3 2 3 4 3 6% 10% 60%	1710
	11th to 20th	Night	5% 3 1 4 4 3 5% 3 5% 9% 57%	1710
	21st to end	Night	6% 5% 1 5% 3 4 5% 4 7% 8% 52%	1710
July	1st to 10th	Night	5% 3 1 4 4 4 4 4 6% 10% 55%	2850
	11th to 20th	Night	4 4 1 4 3 4 4 4 8% 11% 53%	2850
	21st to end	Night	9% 7% 3 6% 5% 5% 5% 4 7% 10% 41%	3098
August	1st to 10th	Night	1 1 2 2 2 2 3 5% 8% 75%	2836
	11th to 20th	Night	3 2 1 3 3 3 4 4 7% 11% 59%	3018
	21st to end	Night	4 3 2 4 3 4 4 4 7% 10% 55%	3699
September	1st to 10th	Night	9% 4 2 6% 4 4 4 4 5% 8% 51%	2090
	11th to 20th	Night	10% 6% 2 6% 4 4 5% 5% 5% 8% 46%	2090
	21st to end	Night	7% 4 2 4 4 4 4 3 6% 8% 54%	2090
October	1st to 10th	Night	5% 3 2 3 3 4 3 3 5% 6% 62%	2090
	11th to 20th	Night	12% 5% 1 4 3 4 2 3 4 6% 55%	2227
	21st to end	Night	14% 4 1 3 3 2 3 2 3 4 60%	2508
November	1st to 10th	Night	14% 5% 2 5% 3 4 3 3 4 6% 52%	2340
	11th to 20th	Night	11% 5% 2 4 4 3 3 3 4 6% 55%	2490
	21st to end	Night	18% 6% 2 4 4 3 3 2 4 6% 47%	2600
December	1st to 10th	Night	22% 9% 3 6% 4 3 3 2 4 4 40%	4250
	11th to 20th	Night	20% 9% 2 5% 3 3 2 2 3 4 47%	4816
	21st to end	Night	18% 6% 2 3 2 2 2 2 3 4 56%	6490

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	38% 3 4 19% 23% 13%	2938
	11th to 20th	Day	32% 2 7% 17% 28% 14%	2940
	21st to end	Day	44% 2 4 10% 28% 11%	3304
February	1st to 10th	Day	44% 3 6% 13% 20% 14%	1900
	11th to 20th	Day	43% 4 7% 16% 18% 12%	1859
	21st to end	Day	41% 4 6% 18% 17% 15%	1570
March	1st to 10th	Day	44% 4 7% 15% 20% 9%	3436
	11th to 20th	Day	53% 6% 7% 10% 16% 8%	3480
	21st to end	Day	40% 5% 9% 16% 22% 8%	3814
April	1st to 10th	Day	44% 5% 7% 16% 15% 12%	2090
	11th to 20th	Day	44% 5% 6% 15% 19% 11%	2066
	21st to end	Day	40% 6% 5% 21% 20% 9%	2408
May	1st to 10th	Day	52% 7% 9% 14% 13% 5%	4120
	11th to 20th	Day	41% 6% 9% 18% 20% 6%	4086
	21st to end	Day	39% 9% 12% 28% 11% 1	4489
June	1st to 10th	Day	29% 8% 14% 27% 20% 3	2470
	11th to 20th	Day	32% 7% 11% 26% 18% 5%	2470
	21st to end	Day	37% 9% 11% 23% 16% 2	2470
July	1st to 10th	Day	30% 6% 18% 38% 7% 1	4056
	11th to 20th	Day	29% 5% 18% 29% 16% 2	4051
	21st to end	Day	40% 6% 18% 28% 8% 1	4325
August	1st to 10th	Day	13% 4 11% 42% 28% 1	4090
	11th to 20th	Day	20% 5% 22% 39% 12% 2	3841
	21st to end	Day	28% 8% 20% 24% 18% 2	3960
September	1st to 10th	Day	38% 6% 10% 21% 16% 9%	2090
	11th to 20th	Day	40% 7% 11% 18% 19% 5%	2090
	21st to end	Day	30% 8% 10% 21% 17% 14%	2090
October	1st to 10th	Day	17% 4 6% 13% 23% 38%	3480
	11th to 20th	Day	21% 3 8% 19% 30% 19%	3186
	21st to end	Day	27% 3 4 20% 31% 15%	3428
November	1st to 10th	Day	39% 5% 8% 18% 19% 11%	1958
	11th to 20th	Day	35% 4 8% 17% 21% 15%	1905
	21st to end	Day	41% 4 6% 17% 19% 13%	1800
December	1st to 10th	Day	50% 2 6% 17% 16% 9%	2940
	11th to 20th	Day	44% 3 6% 11% 23% 12%	3389
	21st to end	Day	35% 2 4 17% 27% 15%	4488
January	1st to 10th	Night	36% 3 6% 16% 22% 17%	4238
	11th to 20th	Night	27% 2 5% 17% 32% 18%	4250
	21st to end	Night	45% 3 5% 13% 24% 11%	4415
February	1st to 10th	Night	41% 4 6% 14% 19% 17%	2280
	11th to 20th	Night	40% 3 6% 17% 19% 15%	2218
	21st to end	Night	42% 4 6% 15% 17% 16%	1882
March	1st to 10th	Night	45% 5% 8% 16% 17% 9%	3419
	11th to 20th	Night	52% 6% 9% 11% 13% 8%	3480
	21st to end	Night	43% 5% 9% 14% 20% 9%	3817
April	1st to 10th	Night	39% 5% 8% 18% 16% 14%	2090
	11th to 20th	Night	40% 5% 9% 15% 16% 15%	2063
	21st to end	Night	39% 4 10% 21% 18% 9%	1766
May	1st to 10th	Night	49% 6% 8% 18% 13% 5%	2850
	11th to 20th	Night	35% 7% 10% 24% 17% 7%	2824
	21st to end	Night	36% 7% 14% 30% 11% 2	3099
June	1st to 10th	Night	19% 7% 18% 30% 23% 3	1710
	11th to 20th	Night	24% 6% 15% 31% 20% 5%	1710
	21st to end	Night	27% 8% 17% 28% 16% 3	1710
July	1st to 10th	Night	24% 6% 25% 38% 6% 1	2805
	11th to 20th	Night	25% 6% 21% 33% 15% 1	2796
	21st to end	Night	37% 6% 23% 28% 7%	2999
August	1st to 10th	Night	10% 4 15% 45% 25% 1	2826
	11th to 20th	Night	19% 5% 30% 32% 12% 2	3045
	21st to end	Night	23% 10% 23% 27% 16% 2	3699
September	1st to 10th	Night	31% 6% 16% 24% 16% 7%	2090
	11th to 20th	Night	35% 8% 13% 22% 15% 6%	2090
	21st to end	Night	27% 7% 16% 20% 18% 13%	2090
October	1st to 10th	Night	16% 4 6% 15% 19% 39%	3480
	11th to 20th	Night	19% 3 9% 17% 30% 21%	3700
	21st to end	Night	24% 2 5% 22% 31% 16%	4120
November	1st to 10th	Night	34% 5% 9% 18% 21% 13%	2340
	11th to 20th	Night	31% 5% 9% 18% 21% 16%	2490
	21st to end	Night	38% 4 7% 18% 18% 15%	2600
December	1st to 10th	Night	50% 3 5% 17% 16% 9%	4250
	11th to 20th	Night	43% 2 7% 9% 23% 16%	4817
	21st to end	Night	35% 3 3 15% 30% 14%	6490

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	18% 10% 37% 24% 10% 1	300
	11th to 20th	Day	24% 8% 28% 27% 10% 2	300
	21st to end	Day	19% 9% 36% 25% 10% 1	300
February	1st to 10th	Day	28% 10% 29% 21% 11% 1	270
	11th to 20th	Day	24% 13% 33% 23% 6% 1	270
	21st to end	Day	26% 10% 42% 20% 3	225
March	1st to 10th	Day	23% 9% 33% 27% 7% 1	270
	11th to 20th	Day	20% 12% 35% 25% 7% 1	270
	21st to end	Day	16% 11% 36% 28% 8% 1	297
April	1st to 10th	Day	19% 12% 37% 24% 7% 1	270
	11th to 20th	Day	21% 8% 34% 23% 13% 1	264
	21st to end	Day	17% 9% 34% 29% 10% 1	588
May	1st to 10th	Day	19% 6% 30% 32% 13%	653
	11th to 20th	Day	18% 5% 24% 33% 17% 4	675
	21st to end	Day	15% 5% 19% 34% 23% 4	734
June	1st to 10th	Day	8% 3 9% 35% 34% 11%	680
	11th to 20th	Day	9% 1 7% 45% 30% 8%	680
	21st to end	Day	6% 3 6% 31% 38% 15%	680
July	1st to 10th	Day	7% 3 5% 29% 40% 17%	671
	11th to 20th	Day	5% 3 26% 50% 16%	668
	21st to end	Day	5% 2 2 26% 47% 19%	739
August	1st to 10th	Day	3 2 2 20% 52% 21%	676
	11th to 20th	Day	6% 1 2 21% 50% 20%	530
	21st to end	Day	6% 1 3 19% 34% 37%	411
September	1st to 10th	Day	8% 1 4 20% 36% 31%	300
	11th to 20th	Day	8% 1 2 20% 37% 32%	300
	21st to end	Day	10% 3 4 20% 37% 26%	300
October	1st to 10th	Day	5% 8% 27% 41% 19%	300
	11th to 20th	Day	13% 15% 32% 28% 12%	300
	21st to end	Day	18% 7% 22% 25% 19% 10%	330
November	1st to 10th	Day	19% 5% 19% 33% 17% 7%	300
	11th to 20th	Day	18% 5% 24% 28% 21% 5%	300
	21st to end	Day	18% 10% 32% 24% 12% 3	300
December	1st to 10th	Day	19% 6% 30% 27% 14% 5%	300
	11th to 20th	Day	23% 10% 26% 26% 14% 1	300
	21st to end	Day	20% 6% 33% 25% 13% 3	330
January	1st to 10th	Night	20% 7% 30% 33% 9% 1	1000
	11th to 20th	Night	20% 8% 30% 33% 8% 1	1000
	21st to end	Night	22% 7% 29% 34% 8%	972
February	1st to 10th	Night	23% 10% 29% 31% 7%	760
	11th to 20th	Night	25% 7% 37% 27% 3	744
	21st to end	Night	27% 11% 37% 23% 2	626
March	1st to 10th	Night	21% 9% 34% 32% 4	570
	11th to 20th	Night	22% 7% 33% 33% 5%	570
	21st to end	Night	18% 7% 41% 30% 4	627
April	1st to 10th	Night	17% 8% 39% 33% 4	570
	11th to 20th	Night	21% 7% 39% 29% 4	563
	21st to end	Night	20% 7% 36% 29% 7% 1	570
May	1st to 10th	Night	18% 6% 35% 34% 7%	570
	11th to 20th	Night	16% 3 29% 39% 12% 1	561
	21st to end	Night	15% 3 29% 36% 18%	617
June	1st to 10th	Night	6% 2 14% 49% 28% 1	570
	11th to 20th	Night	6% 1 25% 50% 17% 2	570
	21st to end	Night	6% 3 13% 44% 31% 4	570
July	1st to 10th	Night	8% 2 8% 44% 34% 4	555
	11th to 20th	Night	5% 1 6% 50% 35% 3	552
	21st to end	Night	4 1 5% 48% 38% 4	624
August	1st to 10th	Night	1 1 4 51% 39% 5%	567
	11th to 20th	Night	6% 1 4 47% 38% 5%	564
	21st to end	Night	5% 2 2 37% 48% 7%	627
September	1st to 10th	Night	8% 2 5% 38% 41% 6%	570
	11th to 20th	Night	12% 3 3 33% 45% 4	570
	21st to end	Night	8% 2 8% 39% 39% 4	570
October	1st to 10th	Night	6% 1 8% 45% 35% 5%	570
	11th to 20th	Night	14% 3 15% 41% 25% 2	707
	21st to end	Night	16% 4 23% 31% 23% 2	836
November	1st to 10th	Night	15% 3 18% 42% 22% 1	780
	11th to 20th	Night	14% 5% 24% 38% 18% 2	890
	21st to end	Night	21% 6% 28% 31% 14% 1	1000
December	1st to 10th	Night	21% 5% 25% 37% 11% 1	1000
	11th to 20th	Night	25% 6% 25% 36% 8% 1	1000
	21st to end	Night	21% 6% 28% 36% 9%	1100

Page generated at 2025-01-19 02:06:48. Version ac07

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