Midland
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Midland clear sky chart from 2005-11-06 to 2024-02-05.

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	16% 11% 5% 8% 6% 3 4 4 5% 6% 32%	78388
	Night	17% 13% 6% 9% 7% 3 4 4 4 5% 27%	80432
Transparency	Day	53% 7% 11% 19% 9% 1	78094
	Night	59% 7% 10% 16% 8% 1	80261
Seeing	Day	22% 16% 30% 21% 9% 3	13877
	Night	23% 15% 28% 23% 9% 1	23031

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	17% 19% 11% 9% 8% 3 4 4 4 4 17%	2271
	11th to 20th	Day	11% 17% 9% 17% 12% 6% 6% 4 4 4 11%	2716
	21st to end	Day	17% 21% 10% 12% 8% 4 4 4 4 4 14%	3124
February	1st to 10th	Day	13% 17% 8% 15% 10% 3 4 4 3 5% 17%	1656
	11th to 20th	Day	14% 14% 7% 13% 7% 4 3 5% 4 5% 24%	1573
	21st to end	Day	17% 17% 7% 9% 7% 4 5% 4 4 4 21%	1374
March	1st to 10th	Day	14% 12% 5% 8% 7% 5% 5% 5% 4 5% 30%	1964
	11th to 20th	Day	13% 14% 5% 8% 7% 2 6% 4 5% 6% 32%	1980
	21st to end	Day	18% 10% 4 5% 5% 3 4 4 4 6% 36%	2178
April	1st to 10th	Day	20% 12% 5% 7% 5% 4 4 3 4 5% 31%	2114
	11th to 20th	Day	19% 10% 3 5% 4 3 4 4 5% 5% 37%	2248
	21st to end	Day	21% 10% 4 5% 5% 3 3 4 4 6% 36%	2340
May	1st to 10th	Day	19% 7% 4 6% 5% 3 4 5% 4 7% 37%	2340
	11th to 20th	Day	15% 7% 2 5% 5% 3 4 4 4 6% 44%	2476
	21st to end	Day	13% 7% 2 4 5% 3 4 5% 6% 7% 44%	2725
June	1st to 10th	Day	18% 6% 3 5% 4 3 4 5% 5% 6% 40%	2528
	11th to 20th	Day	12% 6% 2 5% 4 3 5% 5% 5% 9% 43%	2700
	21st to end	Day	16% 6% 2 5% 5% 3 4 4 5% 8% 42%	2700
July	1st to 10th	Day	10% 5% 2 4 4 3 4 5% 6% 8% 48%	2700
	11th to 20th	Day	12% 6% 2 6% 4 3 4 5% 6% 7% 45%	2579
	21st to end	Day	11% 5% 2 6% 5% 4 5% 5% 7% 8% 42%	2596
August	1st to 10th	Day	13% 5% 2 4 5% 3 4 5% 5% 9% 45%	2327
	11th to 20th	Day	12% 5% 3 5% 5% 3 4 5% 6% 10% 44%	2303
	21st to end	Day	13% 6% 2 5% 5% 3 6% 5% 6% 8% 41%	2512
September	1st to 10th	Day	15% 6% 2 6% 5% 3 4 4 5% 7% 42%	2160
	11th to 20th	Day	14% 6% 3 5% 5% 3 4 4 4 8% 44%	2034
	21st to end	Day	17% 7% 3 7% 6% 3 5% 4 5% 6% 37%	1958
October	1st to 10th	Day	22% 8% 3 7% 5% 3 4 4 5% 6% 34%	1800
	11th to 20th	Day	24% 12% 4 8% 6% 4 5% 4 4 6% 22%	1800
	21st to end	Day	30% 15% 5% 8% 5% 3 4 4 4 5% 18%	1975
November	1st to 10th	Day	17% 17% 5% 8% 6% 3 3 4 4 7% 24%	1554
	11th to 20th	Day	20% 17% 6% 9% 7% 4 6% 4 5% 6% 17%	1520
	21st to end	Day	21% 23% 5% 10% 7% 3 6% 4 4 5% 11%	1520
December	1st to 10th	Day	18% 24% 8% 12% 8% 4 5% 4 4 4 9%	1520
	11th to 20th	Day	19% 19% 8% 12% 8% 4 4 3 4 6% 13%	1906
	21st to end	Day	24% 19% 8% 13% 7% 3 4 4 3 3 11%	2617
January	1st to 10th	Night	15% 24% 12% 14% 8% 3 4 3 3 3 10%	4673
	11th to 20th	Night	14% 15% 9% 16% 14% 5% 5% 5% 4 3 10%	4242
	21st to end	Night	18% 18% 9% 10% 9% 4 5% 5% 5% 5% 13%	4532
February	1st to 10th	Night	12% 19% 8% 16% 10% 4 5% 4 4 4 15%	2399
	11th to 20th	Night	13% 16% 8% 11% 8% 4 5% 3 4 4 22%	2273
	21st to end	Night	18% 14% 6% 9% 8% 4 5% 4 4 5% 24%	1880
March	1st to 10th	Night	14% 11% 6% 9% 7% 3 4 4 4 5% 34%	1982
	11th to 20th	Night	14% 13% 6% 9% 7% 3 4 3 4 5% 33%	1979
	21st to end	Night	16% 11% 3 7% 6% 3 4 5% 4 5% 35%	2178
April	1st to 10th	Night	22% 11% 3 7% 6% 3 4 4 5% 5% 30%	1845
	11th to 20th	Night	19% 9% 4 6% 5% 3 4 4 5% 5% 37%	1676
	21st to end	Night	18% 10% 4 7% 6% 3 5% 4 5% 6% 32%	1620
May	1st to 10th	Night	18% 7% 3 5% 5% 4 4 4 6% 7% 38%	1620
	11th to 20th	Night	15% 7% 3 6% 4 3 4 4 5% 6% 43%	1415
	21st to end	Night	11% 4 2 4 5% 4 4 5% 5% 8% 48%	1550
June	1st to 10th	Night	15% 7% 3 5% 6% 3 5% 5% 6% 8% 37%	1427
	11th to 20th	Night	12% 5% 2 4 4 3 5% 5% 6% 11% 43%	1260
	21st to end	Night	15% 6% 3 6% 4 3 5% 4 7% 8% 41%	1260
July	1st to 10th	Night	9% 4 2 4 4 2 4 4 4 7% 55%	1260
	11th to 20th	Night	12% 5% 2 5% 5% 3 4 4 6% 8% 45%	1376
	21st to end	Night	10% 5% 2 4 5% 3 6% 5% 5% 8% 47%	1718
August	1st to 10th	Night	10% 4 2 3 4 3 5% 5% 6% 7% 49%	1611
	11th to 20th	Night	9% 6% 2 5% 5% 3 5% 4 6% 8% 48%	1598
	21st to end	Night	15% 6% 2 6% 5% 3 5% 4 5% 7% 42%	1826
September	1st to 10th	Night	12% 5% 3 6% 5% 3 4 5% 6% 9% 44%	1800
	11th to 20th	Night	15% 6% 2 5% 5% 3 4 4 4 7% 46%	1922
	21st to end	Night	16% 7% 3 6% 6% 3 4 5% 5% 6% 40%	2002
October	1st to 10th	Night	21% 7% 3 7% 6% 3 4 4 4 5% 35%	2160
	11th to 20th	Night	26% 12% 4 7% 5% 4 4 4 4 6% 24%	2160
	21st to end	Night	26% 15% 4 9% 6% 3 4 4 4 5% 19%	2380
November	1st to 10th	Night	21% 14% 4 8% 6% 3 4 3 4 5% 28%	2524
	11th to 20th	Night	18% 18% 7% 9% 7% 4 4 4 5% 5% 20%	2660
	21st to end	Night	22% 21% 8% 8% 7% 3 4 4 3 5% 14%	2660
December	1st to 10th	Night	20% 25% 10% 12% 6% 3 5% 4 4 3 9%	2660
	11th to 20th	Night	16% 21% 8% 13% 6% 3 5% 5% 5% 5% 13%	3288
	21st to end	Night	24% 22% 8% 14% 7% 3 4 3 3 4 8%	5016

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	69% 9% 12% 7% 3	2272
	11th to 20th	Day	72% 12% 6% 6% 4	2716
	21st to end	Day	74% 8% 7% 7% 4	3124
February	1st to 10th	Day	72% 4 8% 12% 4	1656
	11th to 20th	Day	64% 5% 9% 13% 8% 1	1582
	21st to end	Day	67% 5% 9% 14% 5%	1374
March	1st to 10th	Day	56% 6% 14% 14% 10%	1967
	11th to 20th	Day	54% 6% 10% 18% 10% 2	1980
	21st to end	Day	50% 5% 9% 18% 16% 3	2178
April	1st to 10th	Day	56% 4 11% 18% 10% 1	2114
	11th to 20th	Day	50% 4 9% 23% 13% 1	2248
	21st to end	Day	51% 5% 10% 20% 12% 3	2340
May	1st to 10th	Day	47% 5% 11% 21% 13% 2	2340
	11th to 20th	Day	42% 6% 9% 26% 15% 2	2480
	21st to end	Day	38% 9% 13% 23% 14% 3	2725
June	1st to 10th	Day	43% 7% 11% 25% 14%	2528
	11th to 20th	Day	37% 8% 13% 25% 16% 1	2700
	21st to end	Day	41% 8% 13% 24% 14% 1	2700
July	1st to 10th	Day	32% 8% 14% 27% 17% 2	2626
	11th to 20th	Day	37% 7% 13% 31% 10% 1	2500
	21st to end	Day	39% 8% 14% 26% 12% 1	2451
August	1st to 10th	Day	36% 8% 17% 25% 13% 1	2314
	11th to 20th	Day	35% 9% 17% 27% 11%	2303
	21st to end	Day	40% 8% 15% 25% 11% 1	2512
September	1st to 10th	Day	42% 7% 13% 27% 11% 1	2160
	11th to 20th	Day	39% 7% 14% 29% 10%	2034
	21st to end	Day	47% 8% 12% 25% 7%	1958
October	1st to 10th	Day	51% 8% 12% 19% 11% 1	1800
	11th to 20th	Day	63% 8% 11% 12% 6% 1	1800
	21st to end	Day	69% 7% 9% 10% 5%	1975
November	1st to 10th	Day	61% 6% 10% 16% 6%	1554
	11th to 20th	Day	67% 8% 11% 9% 4 1	1520
	21st to end	Day	75% 8% 8% 8% 1	1520
December	1st to 10th	Day	79% 7% 6% 6% 2	1520
	11th to 20th	Day	73% 8% 9% 8% 3	1906
	21st to end	Day	80% 6% 7% 6% 1	2617
January	1st to 10th	Night	79% 7% 5% 6% 2	4673
	11th to 20th	Night	72% 12% 6% 7% 3	4242
	21st to end	Night	71% 9% 10% 7% 3 1	4532
February	1st to 10th	Night	72% 5% 8% 12% 3	2399
	11th to 20th	Night	65% 4 9% 15% 6%	2275
	21st to end	Night	63% 5% 10% 15% 6%	1880
March	1st to 10th	Night	53% 5% 14% 16% 11% 1	1992
	11th to 20th	Night	55% 5% 9% 18% 12% 2	1980
	21st to end	Night	51% 5% 9% 19% 14% 2	2178
April	1st to 10th	Night	56% 4 9% 18% 11% 1	1845
	11th to 20th	Night	49% 4 7% 21% 16% 2	1676
	21st to end	Night	53% 6% 9% 15% 16% 1	1620
May	1st to 10th	Night	45% 4 11% 19% 17% 3	1620
	11th to 20th	Night	42% 6% 8% 22% 20% 2	1416
	21st to end	Night	34% 7% 13% 27% 16% 3	1551
June	1st to 10th	Night	43% 7% 11% 22% 16% 1	1427
	11th to 20th	Night	34% 7% 12% 25% 20% 1	1260
	21st to end	Night	41% 8% 14% 23% 13% 1	1260
July	1st to 10th	Night	28% 7% 12% 28% 22% 3	1225
	11th to 20th	Night	36% 6% 12% 31% 14% 1	1332
	21st to end	Night	35% 8% 12% 29% 15% 1	1622
August	1st to 10th	Night	33% 7% 17% 29% 14% 1	1600
	11th to 20th	Night	33% 9% 16% 25% 17% 1	1598
	21st to end	Night	42% 7% 13% 25% 12% 1	1826
September	1st to 10th	Night	36% 7% 14% 28% 14% 1	1800
	11th to 20th	Night	38% 7% 13% 29% 12%	1922
	21st to end	Night	44% 7% 14% 26% 10%	2002
October	1st to 10th	Night	52% 7% 9% 19% 12% 1	2160
	11th to 20th	Night	61% 8% 11% 16% 5%	2160
	21st to end	Night	66% 7% 8% 12% 6%	2380
November	1st to 10th	Night	59% 6% 10% 18% 7%	2524
	11th to 20th	Night	66% 7% 12% 11% 4 1	2660
	21st to end	Night	72% 8% 10% 8% 2	2660
December	1st to 10th	Night	79% 7% 6% 6% 2	2660
	11th to 20th	Night	72% 8% 11% 8% 1	3288
	21st to end	Night	82% 5% 6% 6% 1	5016

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	20% 31% 31% 13% 5% 1	180
	11th to 20th	Day	21% 28% 34% 12% 5%	236
	21st to end	Day	29% 19% 30% 19% 3	297
February	1st to 10th	Day	28% 31% 29% 9% 3	252
	11th to 20th	Day	25% 28% 40% 6% 1	240
	21st to end	Day	35% 32% 26% 7%	198
March	1st to 10th	Day	21% 23% 39% 13% 4	407
	11th to 20th	Day	25% 18% 35% 17% 4 1	420
	21st to end	Day	29% 19% 29% 16% 6%	462
April	1st to 10th	Day	26% 21% 30% 16% 7% 1	420
	11th to 20th	Day	32% 19% 23% 16% 7% 3	412
	21st to end	Day	29% 17% 32% 14% 5% 2	420
May	1st to 10th	Day	27% 11% 33% 18% 7% 4	423
	11th to 20th	Day	19% 13% 29% 23% 12% 4	447
	21st to end	Day	17% 11% 29% 26% 11% 6%	485
June	1st to 10th	Day	21% 10% 28% 28% 10% 1	458
	11th to 20th	Day	16% 13% 30% 27% 12% 3	630
	21st to end	Day	19% 10% 32% 25% 11% 3	630
July	1st to 10th	Day	11% 9% 29% 30% 18% 4	621
	11th to 20th	Day	15% 10% 27% 28% 15% 6%	499
	21st to end	Day	11% 9% 33% 31% 12% 5%	488
August	1st to 10th	Day	14% 7% 25% 30% 16% 8%	446
	11th to 20th	Day	14% 7% 25% 28% 16% 10%	439
	21st to end	Day	13% 11% 31% 26% 13% 6%	495
September	1st to 10th	Day	16% 10% 26% 28% 14% 7%	450
	11th to 20th	Day	14% 7% 31% 22% 18% 8%	450
	21st to end	Day	16% 17% 24% 27% 11% 5%	450
October	1st to 10th	Day	24% 16% 27% 17% 13% 4	450
	11th to 20th	Day	26% 22% 33% 15% 4	450
	21st to end	Day	36% 19% 29% 12% 3	490
November	1st to 10th	Day	30% 21% 28% 18% 3	214
	11th to 20th	Day	32% 23% 32% 11% 2 1	180
	21st to end	Day	28% 27% 37% 9%	180
December	1st to 10th	Day	31% 28% 26% 13% 2 1	180
	11th to 20th	Day	29% 36% 21% 11% 2 1	180
	21st to end	Day	36% 26% 30% 7% 1	198
January	1st to 10th	Night	27% 26% 30% 13% 5%	901
	11th to 20th	Night	31% 19% 29% 17% 3 1	760
	21st to end	Night	22% 16% 32% 23% 6% 1	836
February	1st to 10th	Night	26% 23% 31% 18% 2	739
	11th to 20th	Night	22% 20% 32% 20% 6%	703
	21st to end	Night	29% 20% 29% 18% 4	592
March	1st to 10th	Night	22% 19% 33% 21% 4	720
	11th to 20th	Night	23% 20% 32% 19% 5% 1	720
	21st to end	Night	22% 13% 31% 25% 8%	792
April	1st to 10th	Night	29% 13% 32% 23% 4	720
	11th to 20th	Night	24% 16% 28% 21% 11%	612
	21st to end	Night	22% 12% 32% 22% 12%	540
May	1st to 10th	Night	21% 9% 23% 33% 13% 1	540
	11th to 20th	Night	19% 9% 27% 32% 12% 1	354
	21st to end	Night	12% 6% 30% 37% 15%	389
June	1st to 10th	Night	16% 8% 31% 33% 12% 1	360
	11th to 20th	Night	13% 9% 25% 37% 16%	360
	21st to end	Night	15% 6% 28% 33% 17% 1	360
July	1st to 10th	Night	10% 8% 16% 45% 20% 1	350
	11th to 20th	Night	10% 8% 30% 29% 21% 2	348
	21st to end	Night	11% 5% 26% 37% 20% 1	538
August	1st to 10th	Night	11% 5% 22% 34% 25% 3	537
	11th to 20th	Night	9% 7% 21% 35% 24% 4	534
	21st to end	Night	17% 7% 24% 28% 22% 2	638
September	1st to 10th	Night	13% 7% 28% 28% 19% 4	720
	11th to 20th	Night	16% 8% 23% 31% 17% 5%	720
	21st to end	Night	19% 11% 23% 30% 13% 4	720
October	1st to 10th	Night	24% 13% 28% 21% 13% 1	720
	11th to 20th	Night	32% 19% 24% 17% 8% 1	720
	21st to end	Night	33% 19% 28% 16% 3	792
November	1st to 10th	Night	30% 17% 28% 18% 6% 1	740
	11th to 20th	Night	27% 24% 29% 15% 5%	760
	21st to end	Night	34% 19% 29% 14% 3 1	760
December	1st to 10th	Night	34% 27% 25% 11% 3	760
	11th to 20th	Night	28% 24% 32% 11% 3 1	760
	21st to end	Night	34% 21% 29% 15% 2	916

Page generated at 2024-02-02 05:20:27. Version ac07

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