Woods Crossroads
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Woods Crossroads clear sky chart from 2005-11-06 to 2025-02-25.

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	13% 6% 2 6% 4 4 4 4 6% 8% 43%	108559
	Night	14% 6% 2 6% 4 4 4 3 5% 7% 45%	110137
Transparency	Day	22% 44% 7% 14% 10% 3	112194
	Night	23% 42% 6% 15% 12% 3	114641
Seeing	Day	18% 14% 30% 23% 11% 3	15502
	Night	17% 12% 29% 28% 12% 1	25195

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	15% 4 1 4 3 3 3 2 4 4 57%	3800
	11th to 20th	Day	12% 7% 2 5% 3 3 4 3 4 5% 52%	4060
	21st to end	Day	13% 8% 3 7% 5% 4 4 3 5% 5% 45%	4466
February	1st to 10th	Day	13% 9% 3 6% 3 4 5% 4 6% 8% 40%	1800
	11th to 20th	Day	21% 7% 2 4 3 3 3 3 4 5% 44%	1878
	21st to end	Day	15% 9% 2 6% 5% 5% 4 4 5% 6% 39%	1610
March	1st to 10th	Day	22% 9% 3 6% 4 3 3 3 5% 6% 36%	3338
	11th to 20th	Day	10% 4 2 4 3 3 4 4 5% 6% 55%	3480
	21st to end	Day	19% 6% 2 5% 4 4 3 4 5% 7% 41%	3910
April	1st to 10th	Day	12% 5% 2 5% 4 3 4 3 5% 6% 50%	2280
	11th to 20th	Day	11% 6% 2 6% 4 4 4 3 5% 7% 49%	2254
	21st to end	Day	14% 6% 2 6% 5% 4 4 3 6% 8% 43%	2280
May	1st to 10th	Day	17% 7% 3 7% 5% 4 5% 4 7% 8% 32%	3824
	11th to 20th	Day	19% 6% 3 7% 5% 5% 5% 4 6% 7% 32%	4237
	21st to end	Day	10% 4 2 5% 4 4 5% 5% 6% 9% 47%	4823
June	1st to 10th	Day	10% 5% 2 5% 4 5% 5% 6% 7% 10% 41%	2660
	11th to 20th	Day	10% 5% 2 6% 4 5% 5% 4 7% 10% 42%	2660
	21st to end	Day	7% 5% 2 6% 5% 6% 5% 5% 8% 11% 40%	2660
July	1st to 10th	Day	6% 5% 2 6% 6% 5% 6% 6% 8% 12% 40%	4440
	11th to 20th	Day	12% 6% 3 8% 5% 5% 6% 5% 7% 11% 33%	4224
	21st to end	Day	10% 6% 3 8% 6% 6% 7% 6% 8% 9% 31%	4466
August	1st to 10th	Day	15% 8% 3 7% 5% 6% 6% 5% 8% 10% 26%	4104
	11th to 20th	Day	11% 5% 3 6% 6% 6% 7% 5% 7% 9% 35%	3743
	21st to end	Day	9% 4 2 5% 4 4 5% 4 7% 10% 47%	4180
September	1st to 10th	Day	13% 6% 2 6% 4 5% 6% 4 6% 8% 42%	2280
	11th to 20th	Day	13% 6% 3 8% 5% 5% 5% 4 6% 6% 41%	2280
	21st to end	Day	20% 8% 3 6% 4 5% 3 3 6% 6% 36%	2022
October	1st to 10th	Day	16% 6% 2 6% 4 3 4 3 4 6% 44%	1900
	11th to 20th	Day	15% 5% 2 5% 3 2 3 2 5% 5% 52%	1900
	21st to end	Day	12% 5% 2 5% 5% 3 4 3 4 5% 53%	2090
November	1st to 10th	Day	14% 6% 2 5% 3 3 4 2 5% 6% 52%	1865
	11th to 20th	Day	14% 6% 2 5% 3 3 3 3 4 7% 49%	1800
	21st to end	Day	15% 4 2 4 4 3 3 3 6% 5% 52%	1695
December	1st to 10th	Day	11% 5% 2 5% 4 3 3 3 5% 6% 54%	2600
	11th to 20th	Day	19% 8% 2 4 3 2 3 2 3 5% 47%	2990
	21st to end	Day	13% 6% 2 5% 3 3 4 3 5% 7% 49%	3960
January	1st to 10th	Night	13% 6% 2 6% 4 3 3 2 4 5% 52%	6142
	11th to 20th	Night	13% 6% 2 6% 3 3 3 2 4 4 54%	5900
	21st to end	Night	17% 7% 2 5% 3 3 3 2 4 5% 50%	6490
February	1st to 10th	Night	16% 8% 3 5% 4 3 4 3 5% 6% 42%	2600
	11th to 20th	Night	21% 7% 2 5% 3 3 3 4 5% 5% 42%	2407
	21st to end	Night	17% 8% 2 5% 3 3 3 3 5% 6% 46%	1939
March	1st to 10th	Night	24% 8% 3 6% 3 3 3 3 5% 6% 36%	3510
	11th to 20th	Night	15% 5% 2 5% 3 4 3 3 4 6% 50%	3480
	21st to end	Night	17% 8% 3 5% 4 3 3 3 3 4 48%	3722
April	1st to 10th	Night	14% 7% 3 6% 4 4 4 4 6% 7% 42%	1900
	11th to 20th	Night	12% 6% 2 5% 4 4 3 2 5% 8% 50%	1875
	21st to end	Night	15% 7% 2 5% 3 4 4 3 6% 7% 45%	1900
May	1st to 10th	Night	19% 8% 3 7% 5% 4 4 4 6% 7% 33%	3098
	11th to 20th	Night	21% 7% 2 6% 5% 3 5% 3 5% 7% 35%	2655
	21st to end	Night	11% 5% 2 6% 3 4 5% 4 6% 10% 44%	2732
June	1st to 10th	Night	11% 5% 2 6% 6% 5% 5% 6% 7% 10% 39%	1520
	11th to 20th	Night	9% 5% 2 5% 4 5% 6% 5% 7% 11% 40%	1520
	21st to end	Night	8% 5% 2 7% 6% 4 5% 5% 7% 9% 43%	1520
July	1st to 10th	Night	8% 4 2 6% 6% 6% 5% 5% 7% 10% 39%	2520
	11th to 20th	Night	11% 6% 2 6% 5% 5% 5% 5% 8% 11% 36%	2732
	21st to end	Night	13% 8% 3 8% 6% 5% 5% 5% 7% 8% 30%	3087
August	1st to 10th	Night	17% 8% 3 7% 6% 5% 5% 4 7% 9% 30%	2825
	11th to 20th	Night	8% 7% 2 7% 5% 5% 5% 4 7% 9% 41%	3052
	21st to end	Night	9% 5% 2 6% 4 4 4 4 6% 9% 48%	3476
September	1st to 10th	Night	11% 5% 2 5% 4 5% 5% 4 7% 7% 46%	1900
	11th to 20th	Night	12% 5% 3 6% 4 4 5% 4 5% 7% 46%	1900
	21st to end	Night	20% 8% 3 7% 4 3 4 4 5% 6% 37%	2152
October	1st to 10th	Night	14% 6% 2 6% 4 3 4 3 5% 6% 46%	2280
	11th to 20th	Night	13% 6% 2 6% 4 3 3 2 4 6% 50%	2280
	21st to end	Night	15% 5% 1 4 3 4 3 2 4 5% 53%	2508
November	1st to 10th	Night	13% 6% 3 6% 4 3 3 3 4 5% 50%	2431
	11th to 20th	Night	16% 7% 2 4 3 4 3 3 5% 5% 48%	2600
	21st to end	Night	13% 4 2 5% 3 4 4 4 4 6% 51%	2703
December	1st to 10th	Night	10% 5% 2 4 3 4 4 3 4 6% 54%	4580
	11th to 20th	Night	18% 7% 3 7% 4 4 4 3 5% 6% 39%	5205
	21st to end	Night	12% 7% 2 6% 4 3 3 3 5% 7% 48%	6996

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	22% 26% 2 20% 19% 11%	3801
	11th to 20th	Day	25% 26% 3 15% 22% 8%	4060
	21st to end	Day	32% 28% 5% 22% 10% 2	4466
February	1st to 10th	Day	17% 62% 4 11% 5% 1	1800
	11th to 20th	Day	19% 61% 3 8% 7% 2	1887
	21st to end	Day	19% 62% 4 7% 6% 2	1610
March	1st to 10th	Day	38% 41% 5% 6% 8% 3	3338
	11th to 20th	Day	13% 41% 4 18% 18% 6%	3480
	21st to end	Day	27% 40% 7% 11% 12% 3	3910
April	1st to 10th	Day	14% 65% 3 9% 7% 2	2280
	11th to 20th	Day	13% 65% 4 10% 7% 2	2254
	21st to end	Day	15% 65% 4 9% 5% 2	2280
May	1st to 10th	Day	33% 42% 8% 13% 3 1	3859
	11th to 20th	Day	33% 41% 8% 14% 4	4241
	21st to end	Day	18% 41% 10% 16% 13% 2	4837
June	1st to 10th	Day	15% 66% 5% 8% 6%	2660
	11th to 20th	Day	12% 65% 7% 10% 7%	2660
	21st to end	Day	12% 64% 7% 11% 7%	2660
July	1st to 10th	Day	22% 42% 17% 11% 6% 2	4370
	11th to 20th	Day	32% 38% 16% 11% 3	4151
	21st to end	Day	31% 39% 8% 10% 11%	4324
August	1st to 10th	Day	34% 39% 12% 12% 2	4091
	11th to 20th	Day	25% 41% 10% 17% 7%	3779
	21st to end	Day	15% 38% 10% 20% 15% 1	4180
September	1st to 10th	Day	17% 60% 7% 9% 5% 1	2280
	11th to 20th	Day	18% 60% 4 9% 7% 2	2280
	21st to end	Day	24% 59% 3 10% 3 1	2022
October	1st to 10th	Day	20% 40% 6% 13% 17% 3	3160
	11th to 20th	Day	12% 37% 3 13% 29% 7%	3140
	21st to end	Day	9% 36% 6% 20% 20% 10%	3428
November	1st to 10th	Day	17% 55% 4 11% 9% 2	1865
	11th to 20th	Day	17% 56% 4 9% 12% 3	1800
	21st to end	Day	16% 56% 3 14% 10% 2	1695
December	1st to 10th	Day	21% 35% 4 20% 13% 5%	2600
	11th to 20th	Day	29% 31% 9% 14% 12% 4	2986
	21st to end	Day	26% 28% 9% 23% 13% 1	3960
January	1st to 10th	Night	27% 26% 2 15% 22% 8%	6142
	11th to 20th	Night	24% 26% 2 18% 24% 6%	5900
	21st to end	Night	28% 28% 4 22% 15% 3	6490
February	1st to 10th	Night	17% 61% 6% 10% 5% 1	2600
	11th to 20th	Night	19% 61% 2 8% 8% 2	2409
	21st to end	Night	15% 62% 4 10% 6% 3	1939
March	1st to 10th	Night	37% 41% 3 10% 7% 1	3510
	11th to 20th	Night	18% 41% 3 14% 19% 6%	3480
	21st to end	Night	25% 39% 3 16% 13% 3	3722
April	1st to 10th	Night	16% 65% 3 6% 9% 1	1900
	11th to 20th	Night	14% 65% 4 10% 7% 1	1875
	21st to end	Night	16% 65% 5% 9% 5% 1	1900
May	1st to 10th	Night	34% 40% 9% 11% 4	3128
	11th to 20th	Night	31% 41% 7% 18% 3	2656
	21st to end	Night	20% 42% 11% 15% 11%	2739
June	1st to 10th	Night	16% 65% 5% 7% 6% 1	1520
	11th to 20th	Night	12% 66% 6% 9% 7% 1	1520
	21st to end	Night	12% 64% 6% 10% 7% 2	1520
July	1st to 10th	Night	25% 44% 11% 12% 6% 1	2480
	11th to 20th	Night	28% 40% 16% 14% 2	2682
	21st to end	Night	36% 39% 6% 10% 9%	2988
August	1st to 10th	Night	36% 39% 11% 12% 2	2814
	11th to 20th	Night	21% 41% 13% 17% 8%	3082
	21st to end	Night	17% 38% 5% 19% 20% 1	3476
September	1st to 10th	Night	15% 61% 9% 8% 4 2	1900
	11th to 20th	Night	17% 60% 4 10% 8% 1	1900
	21st to end	Night	24% 60% 4 9% 3	2152
October	1st to 10th	Night	22% 38% 8% 14% 14% 3	3800
	11th to 20th	Night	11% 37% 4 15% 25% 9%	3779
	21st to end	Night	8% 36% 3 25% 18% 10%	4120
November	1st to 10th	Night	20% 55% 4 10% 9% 2	2431
	11th to 20th	Night	16% 56% 3 9% 9% 6%	2600
	21st to end	Night	14% 56% 4 13% 12% 2	2703
December	1st to 10th	Night	18% 36% 5% 19% 18% 4	4580
	11th to 20th	Night	34% 32% 7% 12% 9% 4	5208
	21st to end	Night	28% 27% 9% 23% 12%	6996

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	29% 27% 32% 11% 2	244
	11th to 20th	Day	26% 34% 29% 11% 1	300
	21st to end	Day	21% 28% 41% 8% 2	330
February	1st to 10th	Day	24% 28% 37% 8% 3	300
	11th to 20th	Day	33% 25% 31% 11% 1	426
	21st to end	Day	30% 21% 32% 13% 4	398
March	1st to 10th	Day	23% 27% 33% 13% 4	460
	11th to 20th	Day	25% 25% 32% 12% 5% 1	460
	21st to end	Day	22% 23% 36% 15% 4 1	506
April	1st to 10th	Day	22% 26% 33% 13% 5% 1	460
	11th to 20th	Day	15% 18% 37% 21% 6% 3	452
	21st to end	Day	20% 16% 39% 19% 5% 1	460
May	1st to 10th	Day	18% 18% 39% 18% 6% 2	463
	11th to 20th	Day	20% 13% 35% 23% 8% 1	487
	21st to end	Day	20% 6% 29% 27% 14% 3	529
June	1st to 10th	Day	13% 8% 32% 31% 14% 3	490
	11th to 20th	Day	13% 8% 27% 32% 15% 5%	490
	21st to end	Day	10% 6% 29% 36% 17% 4	490
July	1st to 10th	Day	9% 3 23% 37% 24% 4	485
	11th to 20th	Day	7% 3 21% 39% 24% 6%	484
	21st to end	Day	10% 2 28% 34% 19% 6%	532
August	1st to 10th	Day	12% 5% 24% 34% 20% 5%	486
	11th to 20th	Day	11% 5% 20% 35% 21% 6%	479
	21st to end	Day	9% 4 24% 28% 25% 10%	539
September	1st to 10th	Day	14% 4 24% 28% 18% 11%	490
	11th to 20th	Day	14% 7% 24% 30% 16% 9%	490
	21st to end	Day	28% 11% 25% 22% 10% 3	490
October	1st to 10th	Day	20% 8% 25% 26% 15% 7%	490
	11th to 20th	Day	17% 14% 26% 30% 11% 2	490
	21st to end	Day	15% 14% 35% 22% 11% 4	539
November	1st to 10th	Day	18% 13% 31% 24% 11% 3	448
	11th to 20th	Day	19% 19% 33% 20% 9% 1	400
	21st to end	Day	21% 19% 29% 20% 11% 1	295
December	1st to 10th	Day	24% 21% 38% 14% 5%	200
	11th to 20th	Day	26% 21% 31% 18% 5%	200
	21st to end	Day	21% 25% 31% 15% 8%	220
January	1st to 10th	Night	19% 24% 34% 20% 3	800
	11th to 20th	Night	22% 20% 31% 22% 5%	800
	21st to end	Night	22% 18% 35% 23% 2	880
February	1st to 10th	Night	21% 16% 40% 19% 3	800
	11th to 20th	Night	28% 23% 34% 13% 2	783
	21st to end	Night	24% 20% 34% 18% 3	647
March	1st to 10th	Night	20% 18% 34% 23% 4	760
	11th to 20th	Night	24% 18% 34% 19% 4 1	760
	21st to end	Night	20% 16% 40% 21% 4	836
April	1st to 10th	Night	18% 21% 39% 18% 3	760
	11th to 20th	Night	15% 15% 40% 23% 6% 1	751
	21st to end	Night	19% 11% 35% 28% 6%	760
May	1st to 10th	Night	18% 15% 35% 26% 5% 1	741
	11th to 20th	Night	16% 7% 31% 35% 10% 1	469
	21st to end	Night	15% 4 21% 40% 17% 2	411
June	1st to 10th	Night	12% 2 24% 42% 17% 2	380
	11th to 20th	Night	9% 4 24% 42% 17% 3	380
	21st to end	Night	7% 4 23% 44% 19% 2	380
July	1st to 10th	Night	11% 3 20% 43% 23% 1	370
	11th to 20th	Night	5% 2 15% 45% 30% 3	487
	21st to end	Night	7% 3 22% 40% 25% 3	624
August	1st to 10th	Night	9% 3 17% 41% 26% 4	567
	11th to 20th	Night	12% 3 17% 41% 25% 3	717
	21st to end	Night	10% 4 17% 35% 29% 5%	836
September	1st to 10th	Night	14% 4 17% 38% 23% 4	760
	11th to 20th	Night	14% 4 18% 34% 26% 4	760
	21st to end	Night	25% 6% 22% 27% 18% 2	760
October	1st to 10th	Night	17% 7% 21% 31% 20% 4	760
	11th to 20th	Night	19% 11% 27% 29% 13% 2	760
	21st to end	Night	17% 11% 30% 26% 14% 2	836
November	1st to 10th	Night	17% 10% 28% 29% 14% 2	780
	11th to 20th	Night	19% 14% 31% 28% 8% 1	800
	21st to end	Night	15% 17% 29% 30% 9% 1	800
December	1st to 10th	Night	22% 13% 36% 19% 8% 2	800
	11th to 20th	Night	19% 13% 40% 23% 5%	800
	21st to end	Night	19% 17% 29% 30% 5%	880

Page generated at 2025-02-22 06:51:37. Version ac07

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