Martin State Airport
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Martin State Airport clear sky chart from 2005-11-06 to 2024-04-10.

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	14% 5% 2 5% 4 3 4 5% 6% 8% 44%	83184
	Night	16% 6% 2 5% 5% 3 4 4 5% 7% 44%	85592
Transparency	Day	37% 7% 13% 24% 16% 3	82893
	Night	39% 7% 11% 23% 16% 3	85403
Seeing	Day	16% 10% 25% 27% 16% 5%	14170
	Night	17% 10% 29% 30% 13% 1	23740

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	17% 5% 2 3 3 2 3 3 5% 7% 48%	2517
	11th to 20th	Day	14% 9% 3 6% 6% 4 5% 4 5% 5% 40%	2780
	21st to end	Day	20% 7% 2 5% 4 3 4 4 4 7% 38%	3124
February	1st to 10th	Day	15% 6% 3 5% 6% 4 4 5% 6% 7% 40%	1710
	11th to 20th	Day	18% 7% 3 4 3 2 4 5% 5% 7% 42%	1754
	21st to end	Day	18% 8% 3 6% 5% 2 4 4 4 5% 40%	1570
March	1st to 10th	Day	23% 5% 2 4 4 2 3 4 5% 7% 41%	3274
	11th to 20th	Day	10% 4 2 5% 4 3 4 5% 6% 8% 49%	3480
	21st to end	Day	20% 7% 2 5% 4 3 3 4 5% 5% 43%	3941
April	1st to 10th	Day	15% 5% 3 4 5% 3 5% 5% 6% 7% 43%	2270
	11th to 20th	Day	12% 5% 2 4 5% 3 4 5% 5% 7% 47%	2134
	21st to end	Day	17% 5% 2 4 4 3 4 4 5% 8% 42%	2160
May	1st to 10th	Day	16% 7% 2 4 5% 3 4 5% 6% 8% 40%	2257
	11th to 20th	Day	18% 5% 2 4 5% 3 5% 5% 6% 9% 38%	2478
	21st to end	Day	14% 5% 2 4 5% 3 5% 5% 6% 9% 42%	2725
June	1st to 10th	Day	11% 4 2 5% 5% 3 5% 6% 7% 11% 41%	2520
	11th to 20th	Day	12% 5% 3 5% 5% 3 5% 5% 6% 9% 42%	2520
	21st to end	Day	9% 4 1 3 4 4 5% 6% 8% 10% 46%	2520
July	1st to 10th	Day	8% 4 2 6% 5% 3 5% 6% 7% 10% 45%	2520
	11th to 20th	Day	5% 3 2 4 3 3 5% 7% 8% 12% 48%	2520
	21st to end	Day	8% 5% 2 5% 5% 4 6% 7% 8% 11% 39%	2565
August	1st to 10th	Day	9% 5% 2 5% 5% 4 6% 7% 7% 10% 41%	2327
	11th to 20th	Day	9% 5% 2 5% 5% 4 5% 6% 6% 10% 43%	2174
	21st to end	Day	11% 4 2 5% 5% 3 5% 6% 8% 8% 44%	2376
September	1st to 10th	Day	14% 5% 2 5% 5% 3 4 5% 4 7% 47%	2160
	11th to 20th	Day	11% 4 2 4 4 3 4 3 6% 8% 51%	2160
	21st to end	Day	17% 7% 3 5% 5% 3 4 4 5% 8% 39%	1921
October	1st to 10th	Day	18% 5% 2 5% 3 2 3 3 5% 8% 47%	1800
	11th to 20th	Day	17% 5% 2 4 4 2 3 4 5% 7% 49%	1800
	21st to end	Day	15% 6% 2 5% 4 2 4 4 4 7% 47%	1980
November	1st to 10th	Day	13% 6% 2 4 4 2 3 5% 4 7% 52%	1696
	11th to 20th	Day	14% 6% 2 3 4 3 4 5% 5% 6% 49%	1710
	21st to end	Day	15% 5% 3 4 4 3 4 5% 4 7% 47%	1539
December	1st to 10th	Day	18% 6% 2 5% 4 2 3 4 5% 8% 41%	1520
	11th to 20th	Day	18% 6% 2 4 4 2 4 3 5% 8% 43%	1910
	21st to end	Day	17% 6% 3 5% 6% 4 5% 4 5% 7% 39%	2772
January	1st to 10th	Night	16% 7% 3 5% 4 3 4 4 4 6% 44%	4429
	11th to 20th	Night	19% 7% 2 5% 4 2 3 3 4 6% 44%	4175
	21st to end	Night	22% 7% 2 4 4 2 3 4 4 6% 40%	4532
February	1st to 10th	Night	17% 7% 3 5% 5% 3 4 4 5% 6% 41%	2470
	11th to 20th	Night	18% 7% 3 5% 4 3 3 4 4 6% 43%	2310
	21st to end	Night	18% 7% 2 5% 4 3 4 4 5% 6% 42%	1884
March	1st to 10th	Night	21% 7% 2 4 4 2 3 4 4 6% 40%	3574
	11th to 20th	Night	11% 5% 2 4 4 3 4 5% 5% 7% 51%	3480
	21st to end	Night	16% 7% 3 5% 4 3 3 4 4 4 47%	3690
April	1st to 10th	Night	16% 6% 3 5% 4 3 4 4 5% 8% 41%	1900
	11th to 20th	Night	14% 5% 3 5% 5% 3 4 4 5% 6% 46%	1775
	21st to end	Night	19% 6% 2 3 4 3 3 4 5% 8% 45%	1800
May	1st to 10th	Night	18% 6% 2 4 5% 3 5% 5% 4 8% 39%	1716
	11th to 20th	Night	19% 8% 3 4 4 3 5% 5% 5% 7% 37%	1415
	21st to end	Night	15% 6% 2 5% 5% 3 4 4 7% 10% 41%	1550
June	1st to 10th	Night	12% 4 2 6% 4 3 3 5% 5% 9% 46%	1440
	11th to 20th	Night	11% 5% 2 5% 5% 4 5% 5% 7% 8% 41%	1440
	21st to end	Night	11% 4 3 5% 6% 3 5% 5% 7% 10% 43%	1440
July	1st to 10th	Night	10% 4 3 6% 6% 4 7% 7% 8% 8% 38%	1440
	11th to 20th	Night	6% 4 1 5% 6% 3 6% 7% 7% 11% 43%	1440
	21st to end	Night	8% 4 2 5% 5% 3 6% 6% 7% 10% 43%	1748
August	1st to 10th	Night	9% 4 2 5% 6% 4 5% 8% 7% 10% 39%	1611
	11th to 20th	Night	11% 6% 2 5% 6% 4 6% 6% 7% 7% 40%	1708
	21st to end	Night	12% 6% 2 4 5% 3 5% 6% 6% 9% 42%	1980
September	1st to 10th	Night	14% 7% 2 5% 4 2 4 4 5% 7% 45%	1800
	11th to 20th	Night	11% 6% 2 5% 4 2 4 4 4 7% 52%	1800
	21st to end	Night	17% 6% 3 6% 5% 4 3 4 5% 6% 40%	2035
October	1st to 10th	Night	20% 6% 2 4 5% 3 4 3 4 5% 43%	2160
	11th to 20th	Night	17% 4 2 3 4 2 3 4 4 6% 50%	2160
	21st to end	Night	18% 5% 1 3 3 3 4 4 4 7% 48%	2376
November	1st to 10th	Night	12% 5% 2 4 3 2 4 4 5% 5% 53%	2379
	11th to 20th	Night	16% 5% 2 5% 3 2 3 3 5% 5% 49%	2470
	21st to end	Night	14% 4 2 4 5% 3 4 4 5% 6% 48%	2636
December	1st to 10th	Night	18% 6% 3 5% 5% 3 4 4 5% 6% 41%	2660
	11th to 20th	Night	17% 5% 2 4 5% 3 5% 4 5% 7% 43%	3285
	21st to end	Night	16% 6% 3 5% 5% 3 5% 6% 6% 8% 36%	4884

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% 10% 32% 14% 4	2518
	11th to 20th	Day	45% 5% 10% 22% 14% 4	2780
	21st to end	Day	45% 6% 14% 22% 11% 2	3124
February	1st to 10th	Day	42% 6% 14% 25% 12% 2	1710
	11th to 20th	Day	40% 5% 10% 27% 15% 3	1763
	21st to end	Day	46% 4 12% 20% 14% 4	1570
March	1st to 10th	Day	42% 6% 11% 25% 12% 3	3274
	11th to 20th	Day	30% 6% 10% 29% 20% 4	3480
	21st to end	Day	44% 6% 10% 20% 17% 4	3941
April	1st to 10th	Day	37% 8% 13% 20% 17% 5%	2270
	11th to 20th	Day	35% 6% 12% 23% 18% 6%	2134
	21st to end	Day	39% 7% 13% 19% 18% 4	2160
May	1st to 10th	Day	39% 8% 14% 21% 15% 3	2257
	11th to 20th	Day	41% 9% 15% 19% 13% 3	2482
	21st to end	Day	37% 8% 16% 24% 13% 2	2725
June	1st to 10th	Day	34% 10% 16% 24% 15% 2	2520
	11th to 20th	Day	36% 11% 13% 23% 15% 2	2520
	21st to end	Day	29% 11% 17% 24% 17% 1	2520
July	1st to 10th	Day	33% 11% 16% 22% 16% 3	2450
	11th to 20th	Day	26% 11% 18% 28% 15% 3	2445
	21st to end	Day	34% 11% 17% 21% 15% 2	2422
August	1st to 10th	Day	35% 11% 17% 24% 12% 1	2314
	11th to 20th	Day	34% 9% 17% 23% 15% 2	2174
	21st to end	Day	34% 9% 15% 23% 15% 4	2376
September	1st to 10th	Day	36% 8% 14% 21% 17% 4	2160
	11th to 20th	Day	32% 7% 12% 23% 22% 4	2160
	21st to end	Day	43% 7% 9% 21% 18% 3	1921
October	1st to 10th	Day	36% 6% 13% 24% 18% 3	1800
	11th to 20th	Day	34% 5% 13% 24% 21% 3	1800
	21st to end	Day	37% 4 10% 28% 20% 2	1980
November	1st to 10th	Day	33% 4 13% 27% 19% 3	1696
	11th to 20th	Day	35% 6% 11% 23% 22% 4	1710
	21st to end	Day	38% 5% 10% 28% 16% 2	1539
December	1st to 10th	Day	40% 5% 16% 25% 12% 2	1520
	11th to 20th	Day	39% 5% 11% 31% 11% 2	1906
	21st to end	Day	43% 7% 16% 22% 11% 1	2772
January	1st to 10th	Night	40% 6% 10% 26% 15% 3	4429
	11th to 20th	Night	41% 5% 9% 26% 16% 3	4175
	21st to end	Night	45% 5% 8% 28% 13% 1	4532
February	1st to 10th	Night	43% 5% 13% 24% 14% 1	2470
	11th to 20th	Night	43% 4 9% 21% 18% 5%	2312
	21st to end	Night	43% 4 10% 21% 17% 5%	1884
March	1st to 10th	Night	45% 5% 9% 26% 13% 2	3574
	11th to 20th	Night	31% 7% 11% 30% 17% 4	3480
	21st to end	Night	41% 5% 8% 19% 22% 5%	3690
April	1st to 10th	Night	41% 6% 11% 19% 19% 5%	1900
	11th to 20th	Night	37% 6% 11% 21% 19% 6%	1775
	21st to end	Night	39% 6% 11% 21% 17% 6%	1800
May	1st to 10th	Night	43% 7% 10% 21% 14% 4	1716
	11th to 20th	Night	44% 7% 12% 16% 17% 3	1416
	21st to end	Night	37% 10% 18% 20% 12% 3	1551
June	1st to 10th	Night	35% 8% 13% 25% 18% 2	1440
	11th to 20th	Night	38% 9% 14% 24% 13% 2	1440
	21st to end	Night	35% 9% 13% 24% 17% 2	1440
July	1st to 10th	Night	40% 11% 17% 17% 12% 3	1400
	11th to 20th	Night	31% 12% 17% 23% 15% 3	1392
	21st to end	Night	32% 10% 17% 24% 17% 1	1651
August	1st to 10th	Night	37% 10% 16% 21% 15% 1	1600
	11th to 20th	Night	41% 9% 15% 20% 14% 2	1708
	21st to end	Night	37% 9% 15% 21% 15% 4	1980
September	1st to 10th	Night	38% 8% 11% 21% 16% 5%	1800
	11th to 20th	Night	34% 7% 8% 24% 23% 4	1800
	21st to end	Night	44% 6% 10% 18% 18% 3	2035
October	1st to 10th	Night	43% 6% 10% 21% 18% 3	2160
	11th to 20th	Night	35% 6% 10% 28% 19% 3	2160
	21st to end	Night	36% 6% 10% 25% 20% 3	2376
November	1st to 10th	Night	34% 5% 11% 25% 19% 6%	2379
	11th to 20th	Night	37% 5% 10% 22% 20% 6%	2470
	21st to end	Night	35% 5% 12% 26% 19% 3	2636
December	1st to 10th	Night	43% 6% 11% 24% 14% 2	2660
	11th to 20th	Night	40% 6% 11% 22% 18% 4	3288
	21st to end	Night	41% 9% 15% 24% 10% 1	4884

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	21% 23% 32% 17% 7% 1	180
	11th to 20th	Day	20% 28% 29% 19% 5%	254
	21st to end	Day	17% 19% 42% 16% 5% 1	297
February	1st to 10th	Day	20% 14% 41% 18% 6%	270
	11th to 20th	Day	24% 20% 39% 14% 2	361
	21st to end	Day	24% 20% 33% 19% 4	382
March	1st to 10th	Day	16% 21% 34% 24% 4 1	460
	11th to 20th	Day	19% 19% 33% 22% 6% 1	460
	21st to end	Day	20% 15% 33% 25% 5% 2	506
April	1st to 10th	Day	18% 18% 35% 22% 5% 2	457
	11th to 20th	Day	13% 17% 30% 24% 13% 4	412
	21st to end	Day	20% 12% 31% 26% 10% 1	420
May	1st to 10th	Day	22% 13% 30% 22% 11% 1	423
	11th to 20th	Day	19% 8% 26% 30% 13% 3	447
	21st to end	Day	18% 5% 17% 26% 25% 9%	485
June	1st to 10th	Day	13% 4 24% 28% 24% 8%	450
	11th to 20th	Day	13% 6% 20% 33% 21% 7%	450
	21st to end	Day	10% 2 22% 37% 22% 7%	450
July	1st to 10th	Day	10% 2 13% 32% 29% 13%	445
	11th to 20th	Day	3 1 9% 40% 36% 11%	444
	21st to end	Day	11% 2 16% 34% 30% 7%	488
August	1st to 10th	Day	9% 4 12% 34% 33% 9%	446
	11th to 20th	Day	12% 3 10% 32% 32% 11%	439
	21st to end	Day	9% 2 17% 30% 28% 14%	495
September	1st to 10th	Day	16% 3 17% 23% 26% 14%	450
	11th to 20th	Day	12% 2 19% 30% 25% 12%	450
	21st to end	Day	22% 7% 20% 30% 17% 3	450
October	1st to 10th	Day	22% 6% 18% 27% 20% 8%	450
	11th to 20th	Day	16% 9% 28% 27% 17% 3	450
	21st to end	Day	17% 10% 33% 27% 11% 3	495
November	1st to 10th	Day	16% 10% 33% 25% 12% 5%	377
	11th to 20th	Day	15% 15% 36% 23% 10% 1	370
	21st to end	Day	17% 18% 24% 28% 11% 2	199
December	1st to 10th	Day	18% 15% 37% 24% 5% 1	180
	11th to 20th	Day	19% 21% 29% 23% 9%	180
	21st to end	Day	21% 13% 32% 26% 8% 1	198
January	1st to 10th	Night	19% 15% 42% 21% 3	760
	11th to 20th	Night	23% 14% 33% 26% 4	760
	21st to end	Night	18% 15% 41% 24% 2	836
February	1st to 10th	Night	19% 13% 36% 28% 3	760
	11th to 20th	Night	22% 19% 39% 19% 1	743
	21st to end	Night	22% 17% 37% 20% 3	628
March	1st to 10th	Night	17% 16% 37% 26% 5%	760
	11th to 20th	Night	19% 15% 38% 22% 5% 1	760
	21st to end	Night	19% 10% 40% 24% 6% 1	836
April	1st to 10th	Night	18% 14% 41% 21% 6%	760
	11th to 20th	Night	15% 10% 34% 31% 9%	711
	21st to end	Night	21% 9% 30% 31% 8%	720
May	1st to 10th	Night	20% 9% 27% 33% 10% 1	636
	11th to 20th	Night	19% 7% 28% 34% 12%	354
	21st to end	Night	15% 4 18% 37% 23% 2	389
June	1st to 10th	Night	13% 2 24% 37% 23% 1	360
	11th to 20th	Night	9% 3 25% 40% 23% 1	360
	21st to end	Night	11% 1 18% 49% 18% 2	360
July	1st to 10th	Night	10% 3 16% 36% 32% 3	350
	11th to 20th	Night	7% 1 10% 43% 35% 3	348
	21st to end	Night	9% 2 15% 43% 30% 2	568
August	1st to 10th	Night	11% 2 13% 40% 32% 3	537
	11th to 20th	Night	12% 3 15% 36% 30% 4	644
	21st to end	Night	13% 2 15% 34% 30% 6%	792
September	1st to 10th	Night	16% 3 17% 32% 27% 5%	720
	11th to 20th	Night	13% 3 14% 36% 30% 5%	720
	21st to end	Night	19% 6% 21% 32% 21% 2	720
October	1st to 10th	Night	22% 5% 21% 29% 19% 5%	720
	11th to 20th	Night	18% 8% 27% 31% 15% 1	720
	21st to end	Night	19% 10% 31% 26% 13% 1	792
November	1st to 10th	Night	15% 6% 33% 31% 12% 2	740
	11th to 20th	Night	19% 14% 29% 29% 9% 1	760
	21st to end	Night	15% 14% 32% 29% 8% 1	760
December	1st to 10th	Night	21% 13% 36% 22% 8%	760
	11th to 20th	Night	17% 11% 41% 25% 6%	760
	21st to end	Night	19% 11% 36% 31% 3	836

Page generated at 2024-04-07 09:28:13. Version ac07

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