Webster State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Webster State Park clear sky chart from 2005-11-06 to 2024-12-02.

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	9% 5% 2 5% 3 3 4 3 5% 7% 54%	105548
	Night	8% 5% 2 5% 3 3 3 3 5% 7% 55%	102704
Transparency	Day	29% 5% 12% 27% 21% 5%	105304
	Night	28% 5% 13% 26% 22% 6%	102538
Seeing	Day	11% 8% 30% 32% 16% 3	15747
	Night	10% 8% 34% 37% 10%	25684

By Month

Percentage Cloud Cover SW (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	7% 10% 3 7% 3 4 4 3 5% 7% 49%	2538
	11th to 20th	Day	7% 11% 3 7% 5% 4 4 3 5% 5% 44%	2737
	21st to end	Day	6% 11% 3 6% 4 3 2 2 4 6% 53%	3135
February	1st to 10th	Day	8% 10% 3 8% 5% 3 4 3 5% 7% 44%	1805
	11th to 20th	Day	5% 7% 2 6% 6% 4 5% 3 5% 7% 49%	1849
	21st to end	Day	7% 6% 1 6% 4 3 3 3 5% 6% 56%	1570
March	1st to 10th	Day	10% 6% 2 4 3 2 2 3 4 5% 59%	3153
	11th to 20th	Day	10% 6% 2 4 3 3 3 3 3 5% 59%	3480
	21st to end	Day	12% 7% 2 4 3 3 4 3 5% 7% 49%	3814
April	1st to 10th	Day	9% 5% 1 4 3 3 3 4 5% 7% 54%	2225
	11th to 20th	Day	11% 6% 2 6% 4 4 3 4 5% 7% 48%	2306
	21st to end	Day	16% 5% 2 4 3 3 4 3 4 7% 47%	2470
May	1st to 10th	Day	13% 5% 2 4 4 3 4 4 6% 7% 49%	4120
	11th to 20th	Day	12% 5% 2 5% 4 4 4 4 6% 7% 49%	4082
	21st to end	Day	13% 5% 2 5% 4 4 5% 4 6% 8% 46%	4489
June	1st to 10th	Day	5% 3 1 4 3 3 4 3 6% 8% 61%	2484
	11th to 20th	Day	7% 4 2 3 3 4 4 4 6% 7% 57%	2660
	21st to end	Day	5% 3 1 4 3 3 4 4 7% 7% 60%	2660
July	1st to 10th	Day	7% 5% 2 5% 4 4 4 4 6% 7% 52%	4430
	11th to 20th	Day	4 2 2 4 4 4 4 4 7% 10% 55%	4291
	21st to end	Day	5% 3 1 3 3 3 4 4 7% 10% 57%	4466
August	1st to 10th	Day	12% 6% 2 5% 3 3 3 3 5% 8% 50%	4103
	11th to 20th	Day	10% 5% 2 5% 4 4 4 4 6% 8% 49%	4041
	21st to end	Day	5% 3 1 4 3 3 4 3 5% 7% 62%	4217
September	1st to 10th	Day	11% 4 1 4 2 3 3 2 4 6% 59%	2182
	11th to 20th	Day	9% 4 1 4 4 4 3 2 5% 6% 59%	2090
	21st to end	Day	8% 4 1 5% 3 3 3 3 4 6% 62%	2090
October	1st to 10th	Day	10% 2 1 2 1 1 2 1 3 5% 71%	3480
	11th to 20th	Day	6% 3 1 3 3 3 4 3 4 7% 65%	3181
	21st to end	Day	8% 4 1 4 2 2 2 3 4 6% 64%	3186
November	1st to 10th	Day	8% 4 1 4 3 3 4 4 4 6% 61%	1763
	11th to 20th	Day	7% 5% 1 3 2 3 3 3 4 5% 64%	1800
	21st to end	Day	10% 6% 2 4 2 2 2 3 4 6% 59%	1800
December	1st to 10th	Day	7% 6% 3 5% 3 3 3 3 6% 7% 54%	1719
	11th to 20th	Day	8% 7% 2 5% 3 4 3 3 5% 6% 55%	2161
	21st to end	Day	11% 14% 4 10% 4 4 4 3 4 5% 38%	2971
January	1st to 10th	Night	6% 9% 5% 13% 3 3 3 2 4 5% 47%	4417
	11th to 20th	Night	5% 7% 2 7% 5% 4 3 3 5% 6% 54%	4213
	21st to end	Night	8% 10% 3 6% 3 4 4 3 4 5% 51%	4532
February	1st to 10th	Night	8% 8% 3 6% 6% 4 4 3 5% 5% 47%	2390
	11th to 20th	Night	5% 7% 3 6% 5% 4 4 4 6% 6% 49%	2218
	21st to end	Night	6% 6% 2 7% 4 3 3 3 4 5% 58%	1884
March	1st to 10th	Night	10% 5% 1 4 2 2 3 2 4 6% 61%	3707
	11th to 20th	Night	8% 5% 2 4 3 3 3 3 6% 8% 56%	3480
	21st to end	Night	12% 7% 1 5% 3 4 3 3 5% 7% 49%	3817
April	1st to 10th	Night	9% 6% 2 5% 3 3 4 4 6% 7% 52%	1952
	11th to 20th	Night	13% 5% 2 5% 4 3 3 4 6% 7% 48%	1821
	21st to end	Night	15% 4 1 5% 4 3 4 3 5% 7% 49%	1710
May	1st to 10th	Night	17% 6% 2 4 4 4 4 5% 5% 6% 45%	2850
	11th to 20th	Night	11% 6% 2 5% 4 4 4 3 5% 7% 49%	2823
	21st to end	Night	12% 4 2 5% 4 4 5% 4 7% 10% 44%	3098
June	1st to 10th	Night	6% 3 1 4 3 3 4 4 6% 11% 56%	1690
	11th to 20th	Night	7% 2 1 4 3 4 5% 3 7% 10% 54%	1520
	21st to end	Night	5% 3 1 5% 4 3 5% 5% 8% 7% 55%	1520
July	1st to 10th	Night	9% 4 1 5% 5% 4 4 3 5% 8% 51%	2540
	11th to 20th	Night	4 3 1 4 3 5% 5% 4 7% 11% 53%	2663
	21st to end	Night	4 3 1 3 3 3 4 4 6% 9% 60%	3097
August	1st to 10th	Night	6% 4 2 5% 3 4 4 4 8% 10% 50%	2836
	11th to 20th	Night	9% 6% 1 5% 4 3 4 3 5% 8% 52%	2798
	21st to end	Night	3 3 1 5% 4 4 4 4 8% 10% 55%	3445
September	1st to 10th	Night	7% 3 2 3 3 3 3 3 5% 7% 63%	1997
	11th to 20th	Night	8% 3 2 4 2 3 4 4 4 6% 61%	2090
	21st to end	Night	7% 3 1 4 3 3 3 2 4 6% 64%	2090
October	1st to 10th	Night	6% 2 1 2 2 2 2 2 3 3 74%	3480
	11th to 20th	Night	6% 2 1 3 2 2 3 2 4 6% 68%	3705
	21st to end	Night	6% 3 1 3 2 2 2 3 4 7% 67%	4367
November	1st to 10th	Night	6% 3 1 3 3 3 2 2 4 6% 66%	2535
	11th to 20th	Night	7% 4 1 3 3 2 3 3 4 5% 64%	2600
	21st to end	Night	8% 6% 1 4 3 2 3 3 4 6% 60%	2600
December	1st to 10th	Night	5% 6% 2 5% 4 3 3 3 5% 6% 57%	2496
	11th to 20th	Night	7% 4 2 4 3 3 3 3 4 7% 59%	3036
	21st to end	Night	12% 13% 3 5% 3 3 3 3 4 5% 45%	4687

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	35% 5% 14% 29% 15% 2	2539
	11th to 20th	Day	39% 7% 13% 24% 12% 5%	2737
	21st to end	Day	34% 4 16% 30% 15% 2	3135
February	1st to 10th	Day	39% 5% 15% 23% 14% 4	1805
	11th to 20th	Day	34% 5% 15% 25% 16% 5%	1859
	21st to end	Day	29% 4 11% 25% 23% 7%	1570
March	1st to 10th	Day	28% 3 8% 22% 30% 8%	3153
	11th to 20th	Day	29% 5% 9% 27% 25% 4	3480
	21st to end	Day	33% 8% 21% 29% 9% 1	3814
April	1st to 10th	Day	28% 5% 12% 27% 22% 5%	2225
	11th to 20th	Day	34% 5% 14% 25% 17% 5%	2309
	21st to end	Day	36% 6% 12% 27% 17% 2	2470
May	1st to 10th	Day	32% 8% 13% 27% 12% 9%	4120
	11th to 20th	Day	32% 8% 15% 28% 15% 1	4086
	21st to end	Day	33% 10% 15% 23% 18% 3	4489
June	1st to 10th	Day	20% 7% 19% 35% 15% 4	2484
	11th to 20th	Day	25% 6% 13% 28% 20% 7%	2660
	21st to end	Day	21% 8% 11% 28% 25% 7%	2660
July	1st to 10th	Day	31% 5% 10% 25% 22% 7%	4361
	11th to 20th	Day	22% 5% 14% 28% 26% 5%	4216
	21st to end	Day	22% 5% 14% 25% 24% 10%	4325
August	1st to 10th	Day	34% 4 13% 27% 19% 3	4090
	11th to 20th	Day	33% 5% 17% 23% 19% 3	4080
	21st to end	Day	22% 4 13% 27% 25% 9%	4216
September	1st to 10th	Day	28% 4 8% 25% 25% 9%	2182
	11th to 20th	Day	27% 4 9% 27% 27% 6%	2090
	21st to end	Day	26% 3 9% 29% 27% 6%	2090
October	1st to 10th	Day	20% 2 5% 21% 41% 11%	3480
	11th to 20th	Day	21% 3 10% 36% 20% 10%	3181
	21st to end	Day	23% 3 7% 28% 33% 6%	3186
November	1st to 10th	Day	25% 4 10% 28% 26% 6%	1763
	11th to 20th	Day	24% 2 9% 29% 32% 5%	1800
	21st to end	Day	28% 3 10% 27% 27% 5%	1800
December	1st to 10th	Day	29% 5% 15% 28% 21% 3	1719
	11th to 20th	Day	30% 3 12% 36% 17% 1	2159
	21st to end	Day	48% 5% 9% 20% 15% 3	2971
January	1st to 10th	Night	40% 4 13% 26% 15% 2	4417
	11th to 20th	Night	30% 6% 15% 26% 20% 3	4213
	21st to end	Night	36% 5% 13% 27% 17% 2	4532
February	1st to 10th	Night	37% 5% 14% 22% 16% 6%	2390
	11th to 20th	Night	33% 5% 12% 28% 18% 3	2218
	21st to end	Night	30% 4 9% 22% 24% 11%	1884
March	1st to 10th	Night	25% 4 8% 22% 29% 11%	3707
	11th to 20th	Night	24% 5% 10% 25% 28% 7%	3480
	21st to end	Night	34% 6% 18% 31% 9% 1	3817
April	1st to 10th	Night	29% 6% 13% 22% 24% 5%	1952
	11th to 20th	Night	34% 5% 14% 23% 19% 4	1821
	21st to end	Night	34% 7% 13% 26% 19% 2	1710
May	1st to 10th	Night	35% 9% 12% 22% 14% 7%	2850
	11th to 20th	Night	33% 8% 16% 25% 18% 1	2824
	21st to end	Night	31% 10% 18% 24% 14% 3	3099
June	1st to 10th	Night	21% 8% 18% 30% 19% 3	1690
	11th to 20th	Night	25% 7% 14% 27% 20% 6%	1520
	21st to end	Night	24% 8% 14% 25% 24% 6%	1520
July	1st to 10th	Night	31% 5% 15% 21% 23% 5%	2500
	11th to 20th	Night	25% 5% 15% 27% 22% 5%	2615
	21st to end	Night	20% 5% 17% 24% 25% 11%	2999
August	1st to 10th	Night	28% 5% 16% 25% 23% 4	2826
	11th to 20th	Night	32% 4 18% 26% 17% 3	2825
	21st to end	Night	24% 4 15% 29% 19% 9%	3445
September	1st to 10th	Night	22% 6% 10% 25% 27% 11%	1997
	11th to 20th	Night	24% 6% 9% 24% 28% 9%	2090
	21st to end	Night	23% 3 11% 24% 32% 8%	2090
October	1st to 10th	Night	17% 3 6% 17% 44% 12%	3480
	11th to 20th	Night	19% 2 10% 26% 29% 13%	3705
	21st to end	Night	20% 2 9% 26% 35% 7%	4367
November	1st to 10th	Night	20% 3 11% 28% 28% 10%	2535
	11th to 20th	Night	23% 3 9% 28% 29% 8%	2600
	21st to end	Night	27% 3 10% 28% 25% 8%	2600
December	1st to 10th	Night	28% 5% 12% 29% 22% 4	2496
	11th to 20th	Night	26% 4 10% 37% 21% 2	3037
	21st to end	Night	41% 5% 12% 27% 14% 2	4687

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	10% 7% 40% 29% 12% 2	270
	11th to 20th	Day	13% 12% 32% 31% 11%	270
	21st to end	Day	11% 6% 43% 30% 9% 1	297
February	1st to 10th	Day	17% 11% 40% 25% 8%	270
	11th to 20th	Day	9% 13% 41% 26% 9% 3	270
	21st to end	Day	8% 13% 54% 20% 5%	225
March	1st to 10th	Day	12% 12% 43% 25% 9%	270
	11th to 20th	Day	19% 11% 33% 26% 9% 1	270
	21st to end	Day	18% 12% 43% 21% 5% 1	297
April	1st to 10th	Day	13% 18% 39% 25% 5% 1	405
	11th to 20th	Day	15% 15% 41% 23% 6%	507
	21st to end	Day	18% 14% 38% 21% 8% 1	650
May	1st to 10th	Day	15% 9% 32% 31% 12% 1	653
	11th to 20th	Day	17% 9% 31% 26% 14% 3	675
	21st to end	Day	14% 10% 30% 33% 12% 2	734
June	1st to 10th	Day	4 5% 25% 37% 20% 9%	680
	11th to 20th	Day	7% 5% 34% 35% 18% 2	680
	21st to end	Day	5% 6% 32% 39% 17% 1	680
July	1st to 10th	Day	7% 3 21% 38% 25% 6%	671
	11th to 20th	Day	3 3 16% 43% 29% 5%	668
	21st to end	Day	7% 2 15% 40% 30% 7%	739
August	1st to 10th	Day	10% 2 15% 39% 29% 5%	676
	11th to 20th	Day	7% 3 18% 42% 27% 3	665
	21st to end	Day	7% 1 20% 41% 26% 5%	563
September	1st to 10th	Day	11% 3 22% 38% 22% 4	392
	11th to 20th	Day	6% 4 24% 38% 21% 6%	300
	21st to end	Day	10% 6% 27% 29% 22% 6%	300
October	1st to 10th	Day	19% 7% 18% 34% 16% 7%	300
	11th to 20th	Day	5% 11% 41% 25% 13% 4	300
	21st to end	Day	18% 11% 32% 26% 10% 3	330
November	1st to 10th	Day	13% 12% 32% 30% 10% 3	300
	11th to 20th	Day	13% 11% 37% 26% 12% 1	300
	21st to end	Day	18% 8% 33% 27% 12% 2	300
December	1st to 10th	Day	7% 7% 41% 32% 11% 1	273
	11th to 20th	Day	13% 11% 40% 28% 9%	270
	21st to end	Day	18% 13% 33% 28% 8%	297
January	1st to 10th	Night	9% 8% 37% 39% 7% 1	950
	11th to 20th	Night	10% 9% 36% 37% 7% 1	950
	21st to end	Night	10% 8% 42% 34% 6%	1045
February	1st to 10th	Night	13% 9% 40% 32% 7%	870
	11th to 20th	Night	9% 10% 40% 36% 4	744
	21st to end	Night	8% 12% 42% 32% 4	628
March	1st to 10th	Night	12% 13% 38% 32% 5%	746
	11th to 20th	Night	14% 10% 36% 33% 7% 1	570
	21st to end	Night	15% 15% 39% 26% 5%	627
April	1st to 10th	Night	12% 14% 44% 28% 3	570
	11th to 20th	Night	15% 14% 39% 28% 4	563
	21st to end	Night	16% 12% 34% 31% 7%	570
May	1st to 10th	Night	14% 8% 37% 35% 6% 1	570
	11th to 20th	Night	15% 9% 32% 34% 9% 1	561
	21st to end	Night	11% 11% 35% 33% 9% 1	617
June	1st to 10th	Night	6% 6% 35% 39% 13% 1	570
	11th to 20th	Night	7% 6% 39% 37% 10%	570
	21st to end	Night	5% 6% 34% 43% 11%	570
July	1st to 10th	Night	8% 2 24% 46% 20% 1	555
	11th to 20th	Night	4 2 23% 52% 18% 1	552
	21st to end	Night	7% 1 16% 50% 24% 1	624
August	1st to 10th	Night	7% 2 19% 51% 21%	567
	11th to 20th	Night	10% 2 20% 48% 19% 1	564
	21st to end	Night	4 2 23% 50% 21% 1	627
September	1st to 10th	Night	7% 2 30% 46% 13% 2	570
	11th to 20th	Night	8% 3 32% 40% 16% 1	570
	21st to end	Night	9% 6% 30% 40% 15% 1	570
October	1st to 10th	Night	11% 7% 31% 38% 13%	570
	11th to 20th	Night	11% 8% 37% 36% 8%	712
	21st to end	Night	13% 9% 31% 33% 13% 1	982
November	1st to 10th	Night	8% 9% 32% 42% 9% 1	975
	11th to 20th	Night	10% 9% 39% 34% 8%	1000
	21st to end	Night	11% 7% 33% 38% 10% 1	1000
December	1st to 10th	Night	8% 8% 38% 38% 7% 1	960
	11th to 20th	Night	12% 8% 36% 36% 7%	950
	21st to end	Night	14% 10% 34% 35% 6%	1045

Page generated at 2024-11-29 09:43:05. Version ac07

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