Mansfield
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Mansfield clear sky chart from 2005-11-06 to 2024-12-24.

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	15% 11% 4 9% 5% 5% 5% 4 6% 7% 31%	101848
	Night	15% 12% 4 9% 5% 5% 4 4 5% 6% 32%	98270
Transparency	Day	53% 2 10% 22% 11% 1	105436
	Night	53% 2 11% 21% 11% 1	102770
Seeing	Day	26% 16% 29% 18% 9% 3	14829
	Night	24% 15% 28% 23% 9% 1	24226

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	14% 19% 9% 10% 6% 4 4 3 4 5% 24%	2517
	11th to 20th	Day	12% 15% 8% 19% 6% 5% 4 2 4 5% 20%	2656
	21st to end	Day	19% 16% 10% 12% 7% 4 4 3 4 4 17%	3124
February	1st to 10th	Day	14% 15% 5% 13% 8% 6% 5% 3 4 4 23%	1710
	11th to 20th	Day	13% 13% 5% 13% 7% 4 5% 4 5% 5% 25%	1667
	21st to end	Day	17% 14% 4 12% 6% 4 4 3 5% 6% 26%	1570
March	1st to 10th	Day	21% 15% 5% 9% 5% 4 3 2 4 5% 27%	3302
	11th to 20th	Day	10% 17% 6% 9% 5% 4 4 4 4 6% 33%	3480
	21st to end	Day	16% 11% 4 10% 6% 4 5% 4 5% 6% 31%	3909
April	1st to 10th	Day	14% 15% 3 9% 6% 4 4 3 5% 7% 30%	2280
	11th to 20th	Day	17% 12% 4 6% 4 4 5% 4 6% 6% 32%	2254
	21st to end	Day	19% 10% 3 7% 5% 4 3 3 6% 6% 34%	2327
May	1st to 10th	Day	24% 10% 3 7% 4 4 4 3 5% 6% 32%	4219
	11th to 20th	Day	21% 10% 3 9% 5% 5% 5% 4 5% 7% 26%	4398
	21st to end	Day	12% 7% 2 7% 4 5% 5% 4 6% 7% 40%	4837
June	1st to 10th	Day	15% 7% 2 8% 6% 5% 5% 5% 6% 8% 33%	2660
	11th to 20th	Day	13% 7% 3 7% 6% 6% 5% 4 6% 8% 35%	2660
	21st to end	Day	13% 6% 2 7% 5% 5% 6% 5% 6% 9% 34%	2660
July	1st to 10th	Day	8% 6% 2 6% 6% 6% 6% 6% 8% 10% 35%	4440
	11th to 20th	Day	7% 6% 2 7% 6% 7% 6% 5% 8% 11% 36%	4440
	21st to end	Day	10% 7% 3 8% 5% 6% 6% 6% 7% 7% 35%	4635
August	1st to 10th	Day	17% 8% 3 7% 5% 5% 5% 5% 6% 8% 30%	4104
	11th to 20th	Day	14% 8% 3 8% 5% 6% 6% 4 7% 10% 28%	3962
	21st to end	Day	11% 8% 3 6% 5% 5% 4 3 6% 10% 38%	4180
September	1st to 10th	Day	16% 7% 2 7% 4 4 4 4 5% 7% 40%	2280
	11th to 20th	Day	14% 6% 2 6% 5% 4 4 3 5% 7% 44%	2280
	21st to end	Day	20% 8% 2 7% 4 4 5% 4 5% 6% 34%	2000
October	1st to 10th	Day	16% 8% 2 8% 4 5% 5% 4 6% 8% 34%	1900
	11th to 20th	Day	18% 9% 3 9% 5% 4 4 4 5% 6% 33%	1900
	21st to end	Day	21% 13% 3 7% 6% 4 4 4 5% 5% 29%	2085
November	1st to 10th	Day	13% 11% 3 8% 5% 5% 4 2 4 5% 39%	1761
	11th to 20th	Day	14% 14% 4 10% 5% 4 5% 4 6% 6% 28%	1669
	21st to end	Day	15% 15% 5% 9% 6% 5% 4 3 5% 7% 26%	1600
December	1st to 10th	Day	17% 18% 7% 12% 6% 5% 4 4 5% 5% 19%	1600
	11th to 20th	Day	18% 15% 6% 11% 5% 4 4 2 5% 6% 24%	1986
	21st to end	Day	20% 19% 5% 12% 6% 4 4 4 4 5% 15%	2796
January	1st to 10th	Night	13% 16% 7% 12% 6% 5% 5% 3 5% 5% 23%	4429
	11th to 20th	Night	12% 16% 6% 16% 6% 5% 5% 4 5% 5% 20%	4303
	21st to end	Night	19% 16% 6% 15% 7% 5% 4 3 4 4 16%	4532
February	1st to 10th	Night	12% 13% 4 11% 7% 6% 5% 5% 5% 6% 26%	2470
	11th to 20th	Night	12% 14% 6% 11% 7% 5% 5% 3 5% 6% 25%	2397
	21st to end	Night	15% 12% 4 13% 5% 6% 4 4 4 5% 27%	1884
March	1st to 10th	Night	19% 15% 4 9% 5% 5% 4 3 4 4 29%	3536
	11th to 20th	Night	12% 18% 6% 9% 6% 4 4 4 4 6% 27%	3479
	21st to end	Night	14% 13% 4 9% 5% 4 4 2 4 6% 36%	3722
April	1st to 10th	Night	16% 13% 4 9% 6% 4 4 3 4 6% 30%	1900
	11th to 20th	Night	18% 10% 3 7% 5% 4 3 4 6% 6% 35%	1875
	21st to end	Night	16% 9% 3 7% 4 5% 4 3 5% 6% 37%	1867
May	1st to 10th	Night	26% 10% 3 7% 4 3 3 3 4 5% 32%	2719
	11th to 20th	Night	21% 10% 3 8% 5% 4 5% 4 5% 6% 29%	2495
	21st to end	Night	10% 7% 2 8% 5% 5% 5% 4 6% 8% 40%	2738
June	1st to 10th	Night	13% 8% 2 6% 5% 4 4 4 5% 9% 39%	1520
	11th to 20th	Night	11% 7% 2 6% 5% 4 5% 4 7% 9% 40%	1520
	21st to end	Night	11% 5% 2 6% 6% 5% 5% 4 6% 8% 42%	1520
July	1st to 10th	Night	7% 9% 3 8% 5% 6% 4 3 6% 8% 41%	2520
	11th to 20th	Night	8% 4 2 6% 4 5% 6% 4 8% 10% 43%	2520
	21st to end	Night	11% 6% 3 7% 5% 4 5% 3 5% 7% 44%	2914
August	1st to 10th	Night	16% 9% 3 7% 5% 5% 5% 4 6% 6% 36%	2825
	11th to 20th	Night	14% 7% 3 8% 4 4 3 4 4 9% 40%	2835
	21st to end	Night	10% 7% 3 7% 5% 5% 5% 5% 6% 8% 41%	3476
September	1st to 10th	Night	14% 6% 3 6% 3 4 4 3 5% 6% 45%	1900
	11th to 20th	Night	13% 6% 2 5% 3 3 3 2 5% 8% 50%	1900
	21st to end	Night	17% 7% 2 7% 5% 4 4 3 5% 7% 38%	2176
October	1st to 10th	Night	16% 8% 3 6% 5% 4 5% 4 6% 6% 39%	2280
	11th to 20th	Night	17% 10% 3 5% 4 4 4 3 6% 7% 37%	2280
	21st to end	Night	21% 11% 2 8% 4 4 4 3 5% 6% 31%	2510
November	1st to 10th	Night	10% 12% 3 7% 4 4 4 3 5% 6% 41%	2537
	11th to 20th	Night	16% 13% 4 9% 4 5% 5% 4 5% 6% 30%	2730
	21st to end	Night	14% 14% 4 9% 5% 5% 6% 4 5% 7% 27%	2800
December	1st to 10th	Night	15% 16% 6% 11% 7% 5% 5% 4 6% 6% 20%	2800
	11th to 20th	Night	17% 15% 5% 12% 5% 5% 5% 3 4 4 25%	3428
	21st to end	Night	21% 16% 7% 11% 6% 5% 4 3 5% 6% 17%	4933

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	65% 1 8% 19% 4 2	2518
	11th to 20th	Day	71% 2 7% 14% 6% 1	2656
	21st to end	Day	72% 1 8% 13% 5% 1	3124
February	1st to 10th	Day	65% 2 10% 14% 8% 1	1710
	11th to 20th	Day	61% 3 6% 20% 9% 1	1676
	21st to end	Day	59% 2 7% 20% 9% 2	1570
March	1st to 10th	Day	62% 1 7% 22% 6% 1	3305
	11th to 20th	Day	55% 1 11% 21% 9% 3	3480
	21st to end	Day	55% 1 6% 23% 13% 1	3909
April	1st to 10th	Day	56% 2 7% 22% 11% 2	2280
	11th to 20th	Day	52% 3 9% 20% 14% 1	2254
	21st to end	Day	52% 3 7% 20% 15% 3	2327
May	1st to 10th	Day	56% 1 7% 23% 11% 1	4231
	11th to 20th	Day	59% 2 10% 21% 7% 1	4402
	21st to end	Day	43% 3 10% 28% 15% 1	4837
June	1st to 10th	Day	50% 3 10% 22% 14% 1	2660
	11th to 20th	Day	47% 3 13% 23% 12% 1	2660
	21st to end	Day	46% 4 11% 27% 12% 1	2660
July	1st to 10th	Day	43% 3 16% 25% 11% 1	4370
	11th to 20th	Day	41% 3 15% 28% 12%	4365
	21st to end	Day	47% 3 14% 22% 13% 1	4487
August	1st to 10th	Day	52% 3 13% 21% 11%	4091
	11th to 20th	Day	51% 2 13% 25% 8%	4001
	21st to end	Day	43% 3 9% 35% 10% 1	4180
September	1st to 10th	Day	44% 3 10% 27% 14% 2	2280
	11th to 20th	Day	41% 3 9% 26% 19% 1	2280
	21st to end	Day	50% 2 10% 21% 15% 1	2000
October	1st to 10th	Day	46% 2 9% 22% 20% 1	3160
	11th to 20th	Day	48% 1 8% 22% 17% 3	3140
	21st to end	Day	42% 2 14% 28% 13% 1	3411
November	1st to 10th	Day	48% 3 10% 21% 15% 2	1761
	11th to 20th	Day	57% 3 8% 21% 9% 3	1669
	21st to end	Day	60% 2 12% 20% 7% 1	1600
December	1st to 10th	Day	68% 2 10% 13% 7%	1600
	11th to 20th	Day	63% 2 13% 16% 5%	1986
	21st to end	Day	73% 2 8% 14% 3	2796
January	1st to 10th	Night	64% 2 9% 18% 7% 1	4429
	11th to 20th	Night	66% 3 9% 15% 6% 1	4303
	21st to end	Night	73% 2 5% 14% 5%	4532
February	1st to 10th	Night	59% 3 11% 18% 8% 1	2470
	11th to 20th	Night	61% 2 8% 18% 9% 1	2399
	21st to end	Night	61% 1 9% 17% 10% 2	1884
March	1st to 10th	Night	61% 2 9% 19% 8% 1	3546
	11th to 20th	Night	60% 1 11% 20% 7% 1	3480
	21st to end	Night	52% 1 7% 22% 15% 3	3722
April	1st to 10th	Night	57% 3 8% 19% 12% 1	1900
	11th to 20th	Night	50% 3 12% 19% 15% 2	1875
	21st to end	Night	48% 2 10% 23% 15% 2	1867
May	1st to 10th	Night	57% 2 8% 23% 8% 2	2726
	11th to 20th	Night	57% 2 13% 18% 9% 1	2496
	21st to end	Night	44% 3 13% 22% 15% 3	2739
June	1st to 10th	Night	44% 3 10% 26% 16% 1	1520
	11th to 20th	Night	41% 3 15% 26% 13% 2	1520
	21st to end	Night	39% 4 13% 29% 13% 1	1520
July	1st to 10th	Night	43% 3 14% 23% 16% 1	2480
	11th to 20th	Night	37% 3 18% 27% 15%	2472
	21st to end	Night	41% 3 13% 22% 20% 1	2821
August	1st to 10th	Night	49% 4 14% 24% 8%	2814
	11th to 20th	Night	44% 3 15% 28% 11%	2862
	21st to end	Night	42% 3 12% 32% 11% 1	3476
September	1st to 10th	Night	41% 3 10% 29% 15% 2	1900
	11th to 20th	Night	35% 3 12% 29% 19% 2	1900
	21st to end	Night	46% 3 11% 25% 15% 1	2176
October	1st to 10th	Night	49% 2 9% 23% 16% 1	3800
	11th to 20th	Night	42% 2 10% 24% 17% 5%	3779
	21st to end	Night	41% 1 15% 28% 13% 1	4134
November	1st to 10th	Night	44% 3 11% 25% 15% 2	2537
	11th to 20th	Night	56% 2 9% 19% 11% 2	2730
	21st to end	Night	57% 3 13% 21% 6% 1	2800
December	1st to 10th	Night	66% 3 11% 16% 5%	2800
	11th to 20th	Night	64% 2 9% 17% 7%	3428
	21st to end	Night	71% 2 9% 14% 3	4933

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	39% 18% 30% 9% 3 1	180
	11th to 20th	Day	37% 29% 26% 6% 1	220
	21st to end	Day	31% 25% 34% 8% 2	297
February	1st to 10th	Day	35% 27% 32% 5% 1	270
	11th to 20th	Day	38% 27% 32% 3	274
	21st to end	Day	41% 21% 27% 10% 1	382
March	1st to 10th	Day	34% 22% 28% 13% 2	460
	11th to 20th	Day	34% 24% 26% 12% 3	460
	21st to end	Day	35% 22% 26% 11% 3 3	506
April	1st to 10th	Day	35% 20% 28% 12% 4 1	460
	11th to 20th	Day	31% 23% 26% 10% 6% 4	452
	21st to end	Day	33% 18% 28% 14% 5% 2	460
May	1st to 10th	Day	32% 17% 28% 12% 8% 3	463
	11th to 20th	Day	27% 15% 29% 17% 9% 3	487
	21st to end	Day	19% 11% 31% 23% 12% 5%	529
June	1st to 10th	Day	19% 17% 30% 22% 10% 1	490
	11th to 20th	Day	19% 10% 31% 26% 12% 1	490
	21st to end	Day	18% 12% 37% 21% 9% 2	490
July	1st to 10th	Day	14% 6% 31% 29% 16% 5%	485
	11th to 20th	Day	10% 9% 31% 30% 15% 6%	484
	21st to end	Day	14% 6% 38% 27% 11% 5%	532
August	1st to 10th	Day	14% 7% 27% 30% 15% 7%	486
	11th to 20th	Day	16% 7% 27% 28% 15% 7%	479
	21st to end	Day	17% 8% 29% 23% 14% 9%	539
September	1st to 10th	Day	20% 10% 23% 25% 15% 7%	490
	11th to 20th	Day	16% 7% 27% 21% 19% 10%	490
	21st to end	Day	28% 12% 26% 19% 12% 4	490
October	1st to 10th	Day	25% 11% 24% 21% 14% 5%	490
	11th to 20th	Day	28% 14% 32% 16% 7% 2	490
	21st to end	Day	33% 18% 26% 17% 5%	536
November	1st to 10th	Day	26% 21% 26% 17% 10% 1	395
	11th to 20th	Day	35% 21% 27% 13% 3 1	269
	21st to end	Day	33% 28% 33% 6% 2	200
December	1st to 10th	Day	33% 27% 31% 6% 3 1	200
	11th to 20th	Day	38% 26% 29% 8% 1	200
	21st to end	Day	36% 26% 31% 6%	204
January	1st to 10th	Night	24% 25% 35% 13% 3	760
	11th to 20th	Night	28% 22% 30% 18% 3	760
	21st to end	Night	25% 24% 31% 17% 3	836
February	1st to 10th	Night	29% 22% 31% 17% 1	760
	11th to 20th	Night	30% 24% 33% 12% 1	743
	21st to end	Night	32% 20% 29% 17% 2	628
March	1st to 10th	Night	30% 23% 29% 16% 2	760
	11th to 20th	Night	31% 21% 27% 17% 3	760
	21st to end	Night	28% 20% 29% 16% 5% 2	836
April	1st to 10th	Night	28% 19% 31% 18% 3	760
	11th to 20th	Night	27% 16% 31% 18% 7% 1	751
	21st to end	Night	24% 14% 31% 25% 6%	727
May	1st to 10th	Night	29% 11% 22% 29% 9%	508
	11th to 20th	Night	20% 11% 30% 30% 8% 1	374
	21st to end	Night	12% 10% 28% 34% 15% 1	411
June	1st to 10th	Night	16% 8% 27% 33% 16% 1	380
	11th to 20th	Night	18% 7% 21% 40% 13%	380
	21st to end	Night	15% 4 30% 39% 12%	380
July	1st to 10th	Night	11% 4 27% 36% 19% 2	370
	11th to 20th	Night	11% 1 22% 42% 21% 2	368
	21st to end	Night	14% 3 18% 42% 19% 3	516
August	1st to 10th	Night	12% 2 24% 37% 23% 2	567
	11th to 20th	Night	15% 3 17% 35% 26% 4	588
	21st to end	Night	15% 4 20% 36% 23% 3	836
September	1st to 10th	Night	19% 8% 21% 33% 16% 3	760
	11th to 20th	Night	16% 5% 20% 29% 26% 5%	760
	21st to end	Night	21% 10% 25% 26% 16% 3	760
October	1st to 10th	Night	21% 10% 25% 25% 17% 3	760
	11th to 20th	Night	26% 13% 27% 24% 8% 1	760
	21st to end	Night	30% 13% 30% 21% 6%	836
November	1st to 10th	Night	20% 17% 31% 24% 8%	780
	11th to 20th	Night	29% 18% 28% 17% 6% 2	800
	21st to end	Night	27% 19% 30% 20% 3 1	800
December	1st to 10th	Night	31% 23% 28% 14% 4	800
	11th to 20th	Night	30% 20% 30% 18% 2	800
	21st to end	Night	30% 21% 32% 15% 2	851

Page generated at 2024-12-21 04:13:53. Version ac07

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