Summit Lake State Recreation Area
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Summit Lake State Recreation Area clear sky chart from 2005-11-06 to 2024-11-02.

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	11% 7% 3 7% 4 4 4 4 5% 7% 43%	101254
	Night	10% 7% 3 7% 4 4 4 3 5% 7% 47%	97765
Transparency	Day	41% 4 13% 26% 15% 2	101067
	Night	38% 3 13% 27% 17% 3	97623
Seeing	Day	14% 9% 29% 30% 14% 3	15834
	Night	13% 8% 33% 34% 11% 1	25681

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	9% 13% 4 18% 9% 6% 4 3 4 5% 25%	2847
	11th to 20th	Day	8% 12% 5% 11% 6% 5% 7% 4 6% 7% 29%	2850
	21st to end	Day	9% 11% 6% 15% 6% 6% 5% 3 4 6% 28%	3135
February	1st to 10th	Day	10% 12% 5% 10% 6% 5% 4 4 5% 7% 30%	1710
	11th to 20th	Day	8% 11% 4 9% 5% 4 4 4 5% 5% 42%	1691
	21st to end	Day	11% 9% 3 9% 5% 5% 4 3 5% 8% 40%	1570
March	1st to 10th	Day	11% 9% 3 7% 4 4 3 3 4 5% 48%	3371
	11th to 20th	Day	12% 8% 3 5% 3 4 4 3 4 6% 48%	3480
	21st to end	Day	22% 12% 4 10% 5% 4 5% 4 6% 5% 23%	3814
April	1st to 10th	Day	14% 8% 3 7% 4 4 3 3 5% 7% 42%	2146
	11th to 20th	Day	18% 10% 2 5% 4 3 3 3 5% 6% 40%	2385
	21st to end	Day	20% 8% 3 6% 4 4 3 4 5% 7% 38%	2470
May	1st to 10th	Day	17% 8% 3 7% 6% 5% 4 4 6% 7% 33%	4082
	11th to 20th	Day	13% 7% 2 7% 4 4 4 3 5% 5% 46%	4082
	21st to end	Day	14% 6% 3 6% 5% 5% 5% 4 6% 7% 40%	4664
June	1st to 10th	Day	9% 4 2 6% 4 4 4 4 6% 9% 49%	2660
	11th to 20th	Day	10% 5% 2 5% 5% 4 5% 4 6% 8% 45%	2660
	21st to end	Day	8% 5% 2 4 4 4 4 4 6% 9% 49%	2768
July	1st to 10th	Day	13% 5% 2 6% 4 4 5% 4 6% 8% 44%	4257
	11th to 20th	Day	7% 4 2 5% 3 3 4 4 5% 7% 55%	4120
	21st to end	Day	4 3 2 4 3 4 5% 5% 8% 10% 52%	4465
August	1st to 10th	Day	7% 5% 2 6% 5% 5% 5% 4 7% 8% 47%	4104
	11th to 20th	Day	16% 7% 2 6% 4 4 4 4 5% 7% 41%	4041
	21st to end	Day	7% 5% 2 6% 4 4 4 4 6% 8% 52%	4478
September	1st to 10th	Day	12% 4 2 5% 4 3 4 3 4 5% 53%	2205
	11th to 20th	Day	10% 5% 2 5% 4 4 4 2 4 6% 54%	2090
	21st to end	Day	11% 4 1 3 3 2 3 3 5% 6% 57%	2090
October	1st to 10th	Day	14% 5% 2 5% 4 2 4 3 3 6% 51%	1948
	11th to 20th	Day	11% 6% 1 4 4 3 3 2 4 5% 57%	1900
	21st to end	Day	13% 8% 2 6% 3 2 3 4 5% 5% 48%	2085
November	1st to 10th	Day	9% 5% 3 6% 3 3 4 3 5% 6% 54%	1682
	11th to 20th	Day	10% 7% 2 8% 5% 4 4 4 5% 7% 44%	1627
	21st to end	Day	12% 8% 3 6% 4 4 2 3 6% 7% 45%	1520
December	1st to 10th	Day	9% 8% 4 7% 4 4 4 3 5% 7% 45%	1520
	11th to 20th	Day	8% 10% 4 7% 5% 5% 5% 5% 6% 8% 37%	1918
	21st to end	Day	16% 10% 5% 15% 6% 5% 4 3 5% 6% 25%	2819
January	1st to 10th	Night	8% 12% 4 18% 9% 6% 4 3 5% 5% 26%	4108
	11th to 20th	Night	6% 11% 4 9% 5% 5% 8% 4 9% 6% 33%	4120
	21st to end	Night	10% 12% 7% 12% 5% 5% 4 4 5% 6% 31%	4532
February	1st to 10th	Night	10% 11% 4 8% 6% 4 4 3 4 5% 39%	2470
	11th to 20th	Night	8% 9% 3 8% 4 4 5% 3 6% 7% 43%	2393
	21st to end	Night	9% 7% 3 8% 4 4 3 3 5% 5% 49%	1884
March	1st to 10th	Night	11% 7% 3 6% 3 3 3 2 4 5% 52%	3484
	11th to 20th	Night	12% 6% 2 4 3 3 3 3 4 6% 54%	3480
	21st to end	Night	19% 8% 3 9% 5% 4 4 4 5% 8% 31%	3817
April	1st to 10th	Night	13% 7% 2 7% 4 3 3 3 5% 7% 45%	2033
	11th to 20th	Night	13% 7% 3 7% 4 4 3 3 5% 5% 47%	1741
	21st to end	Night	17% 6% 3 6% 4 3 4 3 5% 7% 42%	1710
May	1st to 10th	Night	17% 6% 2 5% 3 3 3 3 5% 6% 46%	2823
	11th to 20th	Night	10% 5% 2 5% 3 3 4 3 6% 7% 51%	2823
	21st to end	Night	15% 6% 2 6% 4 4 4 4 5% 7% 43%	2900
June	1st to 10th	Night	7% 4 1 4 3 3 5% 4 6% 10% 54%	1520
	11th to 20th	Night	8% 5% 1 4 4 4 4 4 5% 9% 52%	1520
	21st to end	Night	4 4 2 4 3 4 4 4 6% 8% 58%	1389
July	1st to 10th	Night	8% 4 1 4 4 3 3 4 5% 9% 54%	2672
	11th to 20th	Night	6% 2 1 3 2 3 3 3 6% 8% 64%	2850
	21st to end	Night	3 3 1 3 3 3 4 4 6% 10% 59%	3098
August	1st to 10th	Night	4 4 1 4 4 4 4 4 6% 10% 54%	2836
	11th to 20th	Night	12% 5% 1 4 3 3 4 3 6% 7% 51%	2798
	21st to end	Night	6% 5% 2 5% 3 4 4 3 5% 7% 55%	3187
September	1st to 10th	Night	9% 3 2 4 3 3 3 3 4 7% 60%	1971
	11th to 20th	Night	9% 3 1 3 3 2 3 3 5% 7% 59%	2090
	21st to end	Night	10% 5% 1 4 3 3 3 2 4 5% 60%	2090
October	1st to 10th	Night	13% 6% 2 5% 3 3 4 3 5% 6% 51%	2213
	11th to 20th	Night	12% 6% 2 4 3 3 2 2 4 5% 56%	2280
	21st to end	Night	14% 6% 2 5% 3 3 2 3 4 6% 52%	2508
November	1st to 10th	Night	7% 4 2 4 3 3 4 3 5% 6% 58%	2431
	11th to 20th	Night	10% 6% 2 5% 4 3 3 4 5% 6% 51%	2550
	21st to end	Night	11% 7% 3 5% 4 3 4 3 5% 6% 50%	2660
December	1st to 10th	Night	8% 9% 3 8% 5% 4 4 3 6% 6% 45%	2660
	11th to 20th	Night	9% 9% 4 6% 5% 4 4 3 5% 7% 45%	3279
	21st to end	Night	16% 13% 6% 12% 4 3 3 2 4 5% 31%	4845

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	62% 2 11% 17% 7%	2848
	11th to 20th	Day	55% 3 12% 24% 7%	2850
	21st to end	Day	56% 6% 14% 17% 7%	3135
February	1st to 10th	Day	53% 4 14% 19% 10% 1	1710
	11th to 20th	Day	45% 3 12% 24% 15% 2	1700
	21st to end	Day	44% 4 11% 24% 13% 3	1570
March	1st to 10th	Day	40% 3 9% 30% 16% 2	3371
	11th to 20th	Day	39% 3 10% 30% 15% 3	3480
	21st to end	Day	62% 3 18% 13% 4 1	3814
April	1st to 10th	Day	44% 3 12% 27% 12% 2	2146
	11th to 20th	Day	45% 3 12% 23% 14% 3	2385
	21st to end	Day	47% 4 10% 27% 13%	2470
May	1st to 10th	Day	50% 3 10% 22% 13% 2	4120
	11th to 20th	Day	41% 3 10% 28% 16% 2	4086
	21st to end	Day	43% 4 14% 23% 16% 1	4677
June	1st to 10th	Day	32% 4 17% 31% 13% 3	2660
	11th to 20th	Day	35% 5% 13% 29% 16% 2	2660
	21st to end	Day	32% 4 14% 32% 15% 4	2768
July	1st to 10th	Day	38% 4 12% 30% 14% 1	4193
	11th to 20th	Day	29% 3 13% 32% 20% 3	4051
	21st to end	Day	23% 7% 17% 29% 22% 3	4325
August	1st to 10th	Day	33% 5% 14% 29% 17% 3	4090
	11th to 20th	Day	42% 4 11% 28% 14% 1	4080
	21st to end	Day	31% 5% 14% 26% 19% 5%	4477
September	1st to 10th	Day	32% 3 11% 31% 19% 4	2205
	11th to 20th	Day	33% 2 10% 35% 19% 1	2090
	21st to end	Day	28% 3 10% 32% 26% 1	2090
October	1st to 10th	Day	36% 2 10% 28% 22% 2	1948
	11th to 20th	Day	31% 2 11% 29% 22% 6%	1900
	21st to end	Day	39% 2 13% 23% 19% 4	2085
November	1st to 10th	Day	31% 3 17% 27% 20% 2	1682
	11th to 20th	Day	40% 3 13% 27% 16% 1	1627
	21st to end	Day	41% 3 13% 28% 14% 2	1520
December	1st to 10th	Day	40% 3 15% 28% 11% 2	1520
	11th to 20th	Day	46% 3 18% 27% 6%	1915
	21st to end	Day	61% 2 11% 19% 6% 1	2819
January	1st to 10th	Night	59% 3 11% 17% 10% 1	4108
	11th to 20th	Night	48% 3 14% 24% 10% 1	4120
	21st to end	Night	53% 5% 13% 19% 9% 1	4532
February	1st to 10th	Night	48% 3 13% 22% 12% 2	2470
	11th to 20th	Night	40% 3 14% 25% 15% 3	2394
	21st to end	Night	38% 2 12% 26% 19% 3	1884
March	1st to 10th	Night	36% 3 9% 28% 23% 2	3484
	11th to 20th	Night	34% 2 7% 32% 20% 5%	3480
	21st to end	Night	52% 4 21% 18% 5% 1	3817
April	1st to 10th	Night	39% 4 11% 26% 18% 2	2033
	11th to 20th	Night	41% 2 11% 26% 17% 3	1741
	21st to end	Night	42% 3 13% 25% 16% 1	1710
May	1st to 10th	Night	40% 3 11% 27% 17% 2	2850
	11th to 20th	Night	34% 3 12% 25% 23% 3	2824
	21st to end	Night	41% 3 13% 22% 17% 3	2908
June	1st to 10th	Night	26% 4 15% 35% 15% 4	1520
	11th to 20th	Night	30% 4 13% 28% 20% 5%	1520
	21st to end	Night	24% 4 15% 34% 19% 3	1389
July	1st to 10th	Night	27% 4 16% 35% 16% 2	2627
	11th to 20th	Night	19% 4 16% 37% 21% 4	2796
	21st to end	Night	19% 7% 17% 33% 22% 2	2999
August	1st to 10th	Night	25% 3 16% 34% 19% 3	2826
	11th to 20th	Night	33% 4 15% 28% 18% 2	2825
	21st to end	Night	29% 4 14% 27% 18% 8%	3187
September	1st to 10th	Night	25% 3 10% 32% 24% 5%	1971
	11th to 20th	Night	24% 4 12% 36% 21% 3	2090
	21st to end	Night	29% 2 8% 30% 27% 4	2090
October	1st to 10th	Night	35% 2 10% 24% 27% 2	2213
	11th to 20th	Night	32% 3 8% 26% 26% 5%	2280
	21st to end	Night	36% 2 12% 25% 22% 3	2508
November	1st to 10th	Night	28% 2 15% 28% 23% 4	2431
	11th to 20th	Night	34% 2 13% 30% 18% 3	2550
	21st to end	Night	36% 3 11% 31% 18% 2	2660
December	1st to 10th	Night	40% 3 13% 31% 12% 1	2660
	11th to 20th	Night	39% 3 16% 34% 8%	3281
	21st to end	Night	58% 3 10% 22% 7% 1	4845

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% 12% 33% 26% 11% 1	270
	11th to 20th	Day	17% 11% 36% 29% 5% 1	270
	21st to end	Day	14% 8% 40% 28% 8% 1	297
February	1st to 10th	Day	16% 19% 33% 27% 5%	270
	11th to 20th	Day	16% 16% 32% 26% 8% 1	270
	21st to end	Day	18% 16% 39% 21% 5%	225
March	1st to 10th	Day	14% 17% 40% 22% 4 3	270
	11th to 20th	Day	23% 15% 34% 20% 8%	270
	21st to end	Day	33% 13% 33% 17% 3 1	297
April	1st to 10th	Day	20% 17% 39% 22% 3	326
	11th to 20th	Day	22% 16% 31% 23% 7% 1	583
	21st to end	Day	23% 15% 30% 20% 10% 1	650
May	1st to 10th	Day	21% 12% 31% 25% 9% 2	653
	11th to 20th	Day	19% 10% 28% 27% 14% 3	675
	21st to end	Day	18% 8% 28% 29% 14% 3	734
June	1st to 10th	Day	7% 7% 25% 37% 19% 5%	680
	11th to 20th	Day	9% 6% 32% 33% 16% 4	680
	21st to end	Day	8% 8% 31% 33% 16% 3	680
July	1st to 10th	Day	9% 3 19% 35% 26% 8%	671
	11th to 20th	Day	7% 4 23% 38% 22% 7%	668
	21st to end	Day	5% 4 19% 43% 26% 4	739
August	1st to 10th	Day	9% 3 22% 36% 24% 5%	676
	11th to 20th	Day	11% 4 23% 37% 23% 3	665
	21st to end	Day	9% 4 21% 40% 22% 4	720
September	1st to 10th	Day	12% 4 25% 39% 16% 3	415
	11th to 20th	Day	8% 5% 33% 32% 16% 5%	300
	21st to end	Day	13% 8% 30% 30% 16% 4	300
October	1st to 10th	Day	18% 5% 33% 24% 15% 6%	300
	11th to 20th	Day	12% 15% 38% 25% 9% 1	300
	21st to end	Day	17% 12% 37% 22% 11% 1	330
November	1st to 10th	Day	14% 12% 39% 23% 10% 3	273
	11th to 20th	Day	13% 14% 41% 24% 8%	270
	21st to end	Day	22% 11% 30% 29% 7% 1	270
December	1st to 10th	Day	10% 14% 37% 27% 10% 1	270
	11th to 20th	Day	16% 11% 33% 29% 10% 1	270
	21st to end	Day	23% 12% 39% 22% 3 1	297
January	1st to 10th	Night	13% 12% 35% 33% 6% 1	950
	11th to 20th	Night	14% 12% 36% 31% 7%	950
	21st to end	Night	17% 8% 38% 30% 7%	1045
February	1st to 10th	Night	18% 10% 36% 32% 4	950
	11th to 20th	Night	13% 11% 39% 33% 5%	919
	21st to end	Night	13% 11% 41% 29% 6%	628
March	1st to 10th	Night	13% 14% 38% 28% 7% 1	613
	11th to 20th	Night	20% 8% 38% 27% 7%	570
	21st to end	Night	21% 11% 35% 28% 5%	627
April	1st to 10th	Night	17% 14% 40% 25% 4	570
	11th to 20th	Night	15% 12% 39% 28% 5%	563
	21st to end	Night	19% 10% 34% 29% 7%	570
May	1st to 10th	Night	17% 8% 32% 35% 8%	570
	11th to 20th	Night	13% 9% 31% 36% 10%	561
	21st to end	Night	15% 6% 30% 35% 12%	617
June	1st to 10th	Night	8% 4 26% 46% 16% 1	570
	11th to 20th	Night	9% 4 34% 40% 12% 1	570
	21st to end	Night	5% 3 34% 42% 17%	570
July	1st to 10th	Night	7% 2 19% 41% 30% 1	555
	11th to 20th	Night	3 2 21% 49% 24% 1	552
	21st to end	Night	4 2 13% 55% 25%	624
August	1st to 10th	Night	7% 2 21% 42% 25% 2	567
	11th to 20th	Night	9% 2 19% 47% 22% 1	564
	21st to end	Night	8% 2 22% 43% 22% 3	627
September	1st to 10th	Night	11% 3 24% 40% 22% 1	570
	11th to 20th	Night	10% 2 30% 40% 16% 1	570
	21st to end	Night	10% 6% 32% 35% 15% 2	570
October	1st to 10th	Night	15% 8% 31% 33% 12% 1	693
	11th to 20th	Night	16% 11% 36% 30% 8%	760
	21st to end	Night	18% 11% 28% 32% 10%	836
November	1st to 10th	Night	9% 10% 35% 36% 9% 1	935
	11th to 20th	Night	14% 10% 40% 29% 6% 1	950
	21st to end	Night	15% 10% 36% 30% 9%	950
December	1st to 10th	Night	13% 11% 39% 31% 6%	950
	11th to 20th	Night	16% 9% 35% 33% 7%	950
	21st to end	Night	19% 11% 36% 28% 6%	1045

Page generated at 2024-10-30 12:19:24. Version ac07

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