Hayes Lake State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hayes Lake State Park clear sky chart from 2005-11-06 to 2026-02-16.

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% 10% 4 9% 6% 5% 5% 4 6% 7% 33%	130961
	Night	10% 11% 4 11% 6% 5% 5% 4 6% 6% 30%	130187
Transparency	Day	47% 7% 14% 22% 9% 1	134407
	Night	51% 6% 13% 21% 9% 1	134839
Seeing	Day	16% 11% 32% 25% 12% 3	17913
	Night	16% 9% 33% 31% 11% 1	27982

By Month

Percentage Cloud Cover NE (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	6% 12% 6% 18% 9% 7% 6% 5% 6% 5% 20%	4124
	11th to 20th	Day	3 13% 6% 15% 9% 10% 11% 8% 7% 6% 12%	4112
	21st to end	Day	4 13% 9% 15% 7% 8% 7% 6% 7% 8% 15%	5277
February	1st to 10th	Day	8% 13% 7% 11% 9% 8% 8% 5% 7% 5% 19%	1890
	11th to 20th	Day	8% 10% 5% 9% 9% 7% 8% 5% 7% 8% 25%	1799
	21st to end	Day	6% 10% 5% 14% 8% 7% 7% 5% 6% 8% 24%	1505
March	1st to 10th	Day	9% 10% 3 9% 7% 6% 5% 4 6% 7% 34%	4762
	11th to 20th	Day	9% 9% 4 12% 7% 5% 5% 4 6% 8% 31%	4980
	21st to end	Day	14% 15% 6% 9% 5% 3 4 3 5% 6% 31%	5464
April	1st to 10th	Day	12% 13% 4 8% 5% 4 5% 3 6% 7% 33%	2384
	11th to 20th	Day	14% 12% 4 9% 6% 5% 5% 4 5% 8% 29%	2572
	21st to end	Day	18% 10% 4 8% 5% 5% 4 3 5% 6% 31%	2600
May	1st to 10th	Day	14% 8% 2 6% 4 4 3 3 5% 6% 45%	6161
	11th to 20th	Day	14% 11% 3 7% 5% 5% 5% 4 6% 7% 35%	6319
	21st to end	Day	15% 9% 2 6% 4 4 4 3 5% 7% 41%	7377
June	1st to 10th	Day	15% 6% 2 7% 5% 4 6% 4 7% 8% 36%	3000
	11th to 20th	Day	15% 7% 3 7% 4 4 5% 4 6% 9% 37%	3000
	21st to end	Day	14% 6% 2 8% 7% 4 6% 5% 7% 7% 35%	3000
July	1st to 10th	Day	7% 5% 2 6% 5% 5% 5% 4 8% 10% 43%	6799
	11th to 20th	Day	11% 6% 2 7% 4 4 4 4 6% 9% 43%	6800
	21st to end	Day	11% 7% 3 7% 4 4 5% 4 6% 8% 42%	7327
August	1st to 10th	Day	10% 6% 3 7% 5% 5% 5% 4 6% 8% 43%	4237
	11th to 20th	Day	12% 5% 2 6% 4 5% 5% 4 6% 8% 43%	4171
	21st to end	Day	14% 5% 2 5% 3 4 4 3 5% 8% 45%	4675
September	1st to 10th	Day	12% 6% 2 5% 4 4 4 3 6% 9% 45%	2430
	11th to 20th	Day	15% 7% 2 7% 5% 4 4 4 6% 8% 38%	2252
	21st to end	Day	18% 7% 3 6% 4 4 3 3 5% 7% 40%	2184
October	1st to 10th	Day	17% 11% 3 7% 4 4 4 3 5% 6% 34%	2000
	11th to 20th	Day	17% 13% 3 8% 4 4 4 3 4 5% 33%	2000
	21st to end	Day	16% 18% 4 10% 4 4 4 3 4 6% 26%	2038
November	1st to 10th	Day	13% 18% 5% 11% 6% 5% 3 4 3 6% 27%	1647
	11th to 20th	Day	11% 18% 5% 14% 6% 5% 4 3 5% 5% 24%	1680
	21st to end	Day	11% 15% 5% 15% 9% 6% 5% 4 5% 4 20%	1680
December	1st to 10th	Day	11% 16% 5% 15% 15% 9% 6% 4 4 5% 11%	2431
	11th to 20th	Day	10% 17% 6% 14% 5% 4 5% 5% 6% 6% 22%	2709
	21st to end	Day	12% 16% 7% 20% 9% 7% 5% 3 4 4 14%	3575
January	1st to 10th	Night	4 12% 6% 19% 9% 9% 7% 5% 6% 6% 18%	8800
	11th to 20th	Night	4 13% 6% 15% 10% 8% 10% 9% 9% 5% 11%	8803
	21st to end	Night	6% 15% 7% 12% 6% 6% 7% 6% 9% 7% 19%	8934
February	1st to 10th	Night	8% 11% 5% 12% 8% 7% 8% 5% 7% 6% 23%	2730
	11th to 20th	Night	7% 10% 4 9% 6% 7% 7% 7% 7% 8% 31%	2599
	21st to end	Night	7% 11% 4 13% 9% 6% 5% 4 6% 7% 29%	2141
March	1st to 10th	Night	8% 12% 4 10% 8% 4 4 4 6% 7% 32%	5087
	11th to 20th	Night	7% 11% 5% 12% 7% 5% 5% 4 6% 7% 30%	4979
	21st to end	Night	12% 16% 6% 12% 5% 4 4 2 4 4 31%	5467
April	1st to 10th	Night	13% 10% 3 6% 6% 4 4 4 5% 6% 39%	2011
	11th to 20th	Night	15% 12% 3 8% 4 4 4 4 4 6% 36%	1779
	21st to end	Night	15% 10% 4 8% 5% 4 5% 4 6% 6% 34%	1800
May	1st to 10th	Night	15% 8% 2 5% 3 3 4 3 4 6% 48%	3797
	11th to 20th	Night	15% 8% 2 7% 4 5% 5% 4 5% 6% 40%	3596
	21st to end	Night	14% 7% 2 6% 4 4 4 3 6% 6% 44%	3517
June	1st to 10th	Night	12% 6% 2 5% 3 4 4 4 6% 9% 45%	1400
	11th to 20th	Night	13% 5% 2 5% 5% 5% 4 4 6% 9% 43%	1400
	21st to end	Night	10% 7% 2 5% 4 5% 4 3 7% 9% 45%	1400
July	1st to 10th	Night	9% 4 1 5% 4 4 4 3 7% 9% 49%	3180
	11th to 20th	Night	6% 4 2 5% 3 4 4 4 6% 9% 54%	3180
	21st to end	Night	8% 6% 2 6% 4 3 5% 5% 6% 10% 45%	3546
August	1st to 10th	Night	5% 4 2 6% 4 4 5% 6% 7% 9% 49%	2920
	11th to 20th	Night	12% 4 1 4 4 3 4 3 6% 8% 50%	2888
	21st to end	Night	10% 6% 3 7% 4 3 4 4 5% 8% 46%	3234
September	1st to 10th	Night	11% 5% 2 4 3 4 3 4 5% 7% 52%	1970
	11th to 20th	Night	12% 6% 2 5% 3 4 4 3 5% 8% 48%	2145
	21st to end	Night	16% 7% 2 5% 4 3 3 4 6% 7% 43%	2200
October	1st to 10th	Night	15% 9% 2 7% 4 4 4 4 5% 8% 38%	2395
	11th to 20th	Night	16% 11% 5% 7% 4 3 4 3 6% 7% 35%	2400
	21st to end	Night	17% 15% 4 9% 6% 4 4 3 5% 6% 28%	2798
November	1st to 10th	Night	13% 15% 4 10% 5% 5% 4 3 5% 6% 29%	2871
	11th to 20th	Night	11% 16% 6% 13% 7% 5% 4 3 5% 6% 24%	2940
	21st to end	Night	11% 15% 5% 14% 8% 5% 4 4 5% 5% 24%	2940
December	1st to 10th	Night	7% 17% 7% 18% 11% 8% 5% 3 4 4 14%	4977
	11th to 20th	Night	8% 16% 5% 14% 9% 7% 5% 5% 6% 6% 18%	5718
	21st to end	Night	12% 15% 7% 20% 8% 5% 5% 3 5% 4 15%	7645

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	64% 6% 9% 14% 7%	4125
	11th to 20th	Day	69% 6% 9% 12% 4	4140
	21st to end	Day	64% 5% 8% 17% 6%	5277
February	1st to 10th	Day	62% 6% 11% 14% 7%	1890
	11th to 20th	Day	52% 7% 13% 17% 9% 1	1808
	21st to end	Day	55% 7% 14% 15% 8% 1	1505
March	1st to 10th	Day	47% 5% 16% 18% 11% 2	4764
	11th to 20th	Day	49% 7% 15% 19% 10%	4980
	21st to end	Day	54% 4 9% 22% 11%	5464
April	1st to 10th	Day	49% 6% 10% 22% 12% 1	2384
	11th to 20th	Day	51% 7% 12% 19% 9% 1	2572
	21st to end	Day	52% 6% 12% 20% 9% 1	2600
May	1st to 10th	Day	38% 7% 13% 25% 18% 1	6172
	11th to 20th	Day	44% 8% 11% 21% 15% 1	6323
	21st to end	Day	40% 7% 9% 26% 15% 3	7377
June	1st to 10th	Day	42% 10% 16% 24% 9% 1	3000
	11th to 20th	Day	43% 7% 17% 24% 9%	3000
	21st to end	Day	44% 9% 18% 23% 5%	3000
July	1st to 10th	Day	33% 8% 25% 29% 5%	6726
	11th to 20th	Day	37% 6% 20% 30% 6%	6719
	21st to end	Day	39% 7% 17% 27% 9%	7115
August	1st to 10th	Day	37% 7% 16% 27% 11% 1	4222
	11th to 20th	Day	36% 8% 21% 30% 4	4210
	21st to end	Day	36% 6% 22% 29% 7%	4674
September	1st to 10th	Day	35% 7% 17% 31% 10%	2430
	11th to 20th	Day	42% 8% 19% 25% 5%	2252
	21st to end	Day	43% 6% 14% 30% 6%	2184
October	1st to 10th	Day	39% 5% 14% 28% 13% 1	3260
	11th to 20th	Day	44% 5% 12% 23% 17%	3240
	21st to end	Day	52% 5% 13% 23% 6%	3271
November	1st to 10th	Day	60% 5% 11% 17% 7% 1	1647
	11th to 20th	Day	62% 6% 14% 12% 6% 1	1680
	21st to end	Day	66% 8% 12% 10% 4	1680
December	1st to 10th	Day	74% 7% 9% 8% 2	2431
	11th to 20th	Day	61% 6% 10% 16% 7%	2710
	21st to end	Day	72% 5% 7% 13% 3	3575
January	1st to 10th	Night	65% 6% 11% 11% 8%	8800
	11th to 20th	Night	67% 6% 7% 15% 5%	8850
	21st to end	Night	60% 5% 10% 18% 7%	8934
February	1st to 10th	Night	57% 6% 12% 16% 8%	2730
	11th to 20th	Night	47% 7% 14% 20% 12%	2600
	21st to end	Night	52% 7% 12% 19% 10%	2141
March	1st to 10th	Night	47% 7% 17% 16% 10% 2	5098
	11th to 20th	Night	49% 7% 15% 17% 12%	4980
	21st to end	Night	57% 5% 9% 19% 11% 1	5467
April	1st to 10th	Night	45% 5% 12% 23% 14% 2	2011
	11th to 20th	Night	48% 5% 10% 20% 15% 2	1779
	21st to end	Night	49% 6% 10% 23% 11% 2	1800
May	1st to 10th	Night	37% 6% 11% 27% 19%	3806
	11th to 20th	Night	42% 8% 10% 21% 17% 1	3597
	21st to end	Night	38% 7% 10% 26% 16% 4	3518
June	1st to 10th	Night	35% 9% 19% 27% 10% 1	1400
	11th to 20th	Night	36% 8% 15% 25% 15% 2	1400
	21st to end	Night	36% 9% 20% 26% 7% 1	1400
July	1st to 10th	Night	29% 9% 23% 29% 9% 1	3145
	11th to 20th	Night	26% 7% 21% 36% 10%	3138
	21st to end	Night	33% 7% 21% 30% 8% 1	3444
August	1st to 10th	Night	29% 7% 19% 33% 11% 1	2911
	11th to 20th	Night	30% 7% 22% 32% 8%	2915
	21st to end	Night	35% 6% 21% 28% 10%	3234
September	1st to 10th	Night	31% 6% 17% 34% 12% 1	1970
	11th to 20th	Night	35% 6% 23% 27% 9%	2145
	21st to end	Night	39% 6% 14% 31% 10%	2200
October	1st to 10th	Night	36% 5% 11% 35% 11% 1	3915
	11th to 20th	Night	42% 4 13% 30% 10%	3899
	21st to end	Night	53% 5% 11% 25% 7%	4523
November	1st to 10th	Night	55% 6% 13% 18% 7% 1	2871
	11th to 20th	Night	61% 5% 13% 14% 6% 1	2940
	21st to end	Night	62% 7% 14% 12% 5%	2940
December	1st to 10th	Night	73% 5% 10% 10% 2	4977
	11th to 20th	Night	63% 6% 9% 12% 10%	5716
	21st to end	Night	71% 6% 7% 13% 3	7645

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	14% 12% 39% 23% 11% 2	330
	11th to 20th	Day	11% 10% 40% 30% 8%	330
	21st to end	Day	16% 10% 38% 25% 9% 2	363
February	1st to 10th	Day	17% 15% 40% 21% 6% 1	330
	11th to 20th	Day	9% 17% 39% 22% 11% 2	315
	21st to end	Day	13% 15% 44% 20% 6% 1	249
March	1st to 10th	Day	15% 11% 39% 25% 9% 1	300
	11th to 20th	Day	16% 13% 37% 19% 13% 2	300
	21st to end	Day	14% 15% 37% 24% 9% 2	330
April	1st to 10th	Day	15% 14% 33% 25% 11% 2	484
	11th to 20th	Day	20% 16% 32% 23% 8% 1	690
	21st to end	Day	21% 10% 32% 26% 10% 1	700
May	1st to 10th	Day	20% 14% 32% 24% 9% 2	703
	11th to 20th	Day	20% 11% 31% 24% 11% 3	725
	21st to end	Day	20% 10% 30% 27% 12% 2	789
June	1st to 10th	Day	15% 13% 27% 28% 13% 4	730
	11th to 20th	Day	15% 12% 37% 25% 9% 2	730
	21st to end	Day	16% 10% 29% 25% 15% 5%	730
July	1st to 10th	Day	10% 7% 28% 27% 21% 7%	721
	11th to 20th	Day	13% 8% 28% 28% 18% 5%	718
	21st to end	Day	8% 6% 29% 31% 18% 7%	794
August	1st to 10th	Day	10% 7% 25% 32% 21% 5%	726
	11th to 20th	Day	13% 8% 25% 28% 19% 7%	715
	21st to end	Day	15% 8% 29% 27% 18% 3	803
September	1st to 10th	Day	15% 10% 32% 26% 14% 2	560
	11th to 20th	Day	16% 10% 39% 25% 8% 1	382
	21st to end	Day	22% 10% 35% 22% 9% 3	330
October	1st to 10th	Day	19% 12% 32% 24% 10% 2	330
	11th to 20th	Day	22% 14% 37% 22% 5%	330
	21st to end	Day	27% 15% 34% 17% 5% 1	363
November	1st to 10th	Day	23% 15% 31% 25% 6%	330
	11th to 20th	Day	24% 18% 34% 19% 5% 1	330
	21st to end	Day	19% 19% 34% 26% 3	330
December	1st to 10th	Day	20% 13% 35% 24% 5% 2	330
	11th to 20th	Day	20% 18% 37% 22% 3	330
	21st to end	Day	18% 12% 36% 21% 11% 2	363
January	1st to 10th	Night	13% 10% 38% 27% 10% 2	1050
	11th to 20th	Night	16% 8% 36% 31% 8% 1	1050
	21st to end	Night	16% 9% 39% 28% 7%	1155
February	1st to 10th	Night	13% 10% 34% 34% 9% 1	1050
	11th to 20th	Night	11% 9% 38% 28% 11% 3	1005
	21st to end	Night	12% 9% 39% 28% 10% 2	821
March	1st to 10th	Night	16% 9% 35% 29% 11% 1	680
	11th to 20th	Night	12% 9% 40% 29% 8% 1	600
	21st to end	Night	19% 8% 30% 29% 12% 2	660
April	1st to 10th	Night	17% 9% 32% 30% 10% 1	600
	11th to 20th	Night	19% 11% 32% 28% 10% 1	593
	21st to end	Night	20% 8% 30% 31% 11%	600
May	1st to 10th	Night	19% 6% 34% 33% 7% 1	600
	11th to 20th	Night	17% 8% 34% 30% 10% 1	591
	21st to end	Night	18% 4 32% 35% 11% 1	650
June	1st to 10th	Night	16% 7% 29% 35% 13% 1	600
	11th to 20th	Night	13% 8% 30% 38% 11%	600
	21st to end	Night	12% 6% 29% 34% 19% 1	600
July	1st to 10th	Night	8% 3 23% 43% 21% 2	585
	11th to 20th	Night	6% 6% 27% 41% 18% 2	582
	21st to end	Night	9% 5% 21% 43% 21% 1	657
August	1st to 10th	Night	7% 3 23% 45% 21% 1	597
	11th to 20th	Night	12% 5% 22% 37% 22% 3	594
	21st to end	Night	12% 7% 27% 35% 18% 1	660
September	1st to 10th	Night	13% 5% 28% 36% 16% 2	600
	11th to 20th	Night	15% 6% 32% 33% 14% 1	600
	21st to end	Night	17% 9% 33% 29% 12% 2	600
October	1st to 10th	Night	21% 10% 33% 29% 7%	795
	11th to 20th	Night	23% 9% 35% 26% 7% 1	800
	21st to end	Night	24% 12% 31% 27% 6% 1	1027
November	1st to 10th	Night	21% 12% 33% 27% 7% 1	1025
	11th to 20th	Night	19% 12% 33% 28% 7% 1	1050
	21st to end	Night	17% 14% 40% 22% 6% 1	1050
December	1st to 10th	Night	15% 10% 38% 28% 9%	1050
	11th to 20th	Night	18% 12% 39% 26% 6% 1	1050
	21st to end	Night	20% 9% 36% 26% 8% 1	1155

Page generated at 2026-02-13 00:42:13. Version ac07

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