Tulsa
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Tulsa clear sky chart from 2005-11-06 to 2025-09-04.

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	11% 6% 2 6% 4 4 4 3 5% 7% 48%	126276
	Night	11% 5% 2 5% 3 3 3 3 5% 7% 54%	122727
Transparency	Day	34% 5% 10% 25% 20% 5%	129928
	Night	30% 4 10% 25% 23% 7%	127138
Seeing	Day	14% 10% 27% 28% 16% 4	16633
	Night	13% 10% 31% 32% 13% 1	26396

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	12% 10% 5% 7% 4 3 3 2 4 5% 45%	4077
	11th to 20th	Day	7% 5% 2 7% 4 3 3 3 4 5% 57%	4080
	21st to end	Day	18% 10% 3 5% 3 2 2 2 3 3 49%	4488
February	1st to 10th	Day	14% 11% 3 7% 4 4 3 2 4 5% 42%	1800
	11th to 20th	Day	14% 7% 3 6% 4 4 4 3 5% 6% 45%	1898
	21st to end	Day	13% 9% 2 5% 4 4 4 3 4 6% 46%	1686
March	1st to 10th	Day	11% 7% 2 5% 3 3 3 2 4 5% 55%	4936
	11th to 20th	Day	8% 6% 2 5% 3 3 3 3 5% 7% 55%	4980
	21st to end	Day	12% 9% 3 7% 4 4 5% 4 6% 7% 39%	5462
April	1st to 10th	Day	11% 7% 2 5% 4 4 4 4 7% 6% 46%	2205
	11th to 20th	Day	14% 6% 3 5% 4 4 5% 3 5% 6% 45%	2374
	21st to end	Day	18% 8% 2 7% 4 3 4 3 5% 6% 41%	2567
May	1st to 10th	Day	19% 8% 2 6% 4 4 4 3 4 6% 40%	5862
	11th to 20th	Day	10% 6% 2 6% 4 4 5% 4 6% 7% 45%	5862
	21st to end	Day	17% 8% 3 7% 5% 5% 5% 4 6% 7% 35%	6434
June	1st to 10th	Day	6% 4 2 6% 5% 5% 5% 5% 7% 9% 48%	2600
	11th to 20th	Day	8% 4 2 6% 5% 5% 5% 4 6% 8% 48%	2600
	21st to end	Day	5% 3 1 4 3 3 5% 4 6% 8% 57%	2600
July	1st to 10th	Day	7% 4 2 6% 4 5% 5% 6% 9% 11% 41%	5900
	11th to 20th	Day	6% 4 2 6% 4 5% 5% 4 6% 9% 48%	5900
	21st to end	Day	4 3 1 4 4 5% 5% 5% 7% 11% 52%	6422
August	1st to 10th	Day	4 3 1 4 3 3 4 4 7% 9% 57%	4234
	11th to 20th	Day	6% 4 1 5% 4 4 5% 4 7% 10% 49%	4171
	21st to end	Day	5% 3 2 5% 3 4 5% 3 6% 8% 56%	4445
September	1st to 10th	Day	10% 6% 2 4 4 3 4 4 5% 6% 54%	2169
	11th to 20th	Day	12% 4 2 5% 3 4 4 3 6% 7% 49%	2090
	21st to end	Day	9% 3 2 5% 4 4 3 3 4 6% 57%	2090
October	1st to 10th	Day	8% 4 2 4 3 3 4 3 4 7% 58%	1967
	11th to 20th	Day	11% 4 2 3 2 2 3 2 4 5% 63%	1900
	21st to end	Day	15% 6% 2 4 3 2 3 2 3 5% 55%	2090
November	1st to 10th	Day	10% 5% 2 4 2 3 3 3 5% 6% 57%	1958
	11th to 20th	Day	10% 6% 2 3 2 3 3 2 3 6% 60%	1810
	21st to end	Day	13% 7% 2 4 3 2 2 3 5% 5% 54%	1800
December	1st to 10th	Day	9% 8% 3 5% 3 3 3 3 4 5% 55%	2940
	11th to 20th	Day	12% 7% 2 6% 4 3 2 3 3 6% 53%	3391
	21st to end	Day	20% 12% 4 8% 4 4 3 2 4 4 34%	4488
January	1st to 10th	Night	14% 7% 3 6% 4 3 3 3 5% 6% 47%	5888
	11th to 20th	Night	6% 4 2 4 3 4 3 3 5% 6% 60%	5900
	21st to end	Night	18% 7% 2 5% 3 3 2 2 3 5% 49%	6490
February	1st to 10th	Night	14% 10% 2 7% 3 3 3 2 4 5% 47%	2600
	11th to 20th	Night	14% 7% 3 6% 3 3 3 2 4 6% 49%	2407
	21st to end	Night	13% 7% 2 5% 3 4 4 3 4 4 51%	1942
March	1st to 10th	Night	14% 7% 2 5% 3 3 3 2 4 4 52%	4919
	11th to 20th	Night	8% 4 1 4 2 2 3 3 4 7% 63%	4980
	21st to end	Night	13% 5% 2 6% 4 4 4 3 5% 7% 48%	5467
April	1st to 10th	Night	12% 5% 1 4 3 3 3 3 5% 7% 53%	2192
	11th to 20th	Night	14% 6% 1 5% 3 3 4 3 4 6% 51%	1975
	21st to end	Night	14% 7% 3 5% 3 3 3 3 4 6% 49%	1830
May	1st to 10th	Night	18% 7% 2 5% 4 3 3 2 4 6% 46%	4053
	11th to 20th	Night	13% 5% 3 5% 3 3 3 3 5% 7% 48%	4053
	21st to end	Night	15% 6% 2 5% 3 3 3 3 6% 8% 46%	4443
June	1st to 10th	Night	6% 4 1 4 4 4 4 4 6% 8% 54%	1800
	11th to 20th	Night	6% 3 2 3 4 3 4 3 7% 11% 55%	1800
	21st to end	Night	3 3 1 3 3 3 4 3 5% 9% 64%	1800
July	1st to 10th	Night	5% 4 2 5% 4 4 4 5% 8% 11% 49%	4078
	11th to 20th	Night	4 3 1 4 4 3 4 3 6% 9% 59%	4077
	21st to end	Night	4 3 1 3 2 2 3 3 6% 9% 62%	4449
August	1st to 10th	Night	2 2 1 3 3 3 4 4 6% 8% 64%	2926
	11th to 20th	Night	4 3 2 5% 5% 4 6% 4 6% 8% 54%	2888
	21st to end	Night	3 2 1 3 2 3 3 3 5% 9% 63%	3455
September	1st to 10th	Night	9% 3 2 5% 3 2 3 3 4 6% 59%	2073
	11th to 20th	Night	10% 4 2 5% 4 4 4 3 5% 7% 51%	2090
	21st to end	Night	8% 4 2 4 3 3 3 3 4 6% 59%	2090
October	1st to 10th	Night	7% 3 2 4 3 3 3 3 5% 6% 62%	2193
	11th to 20th	Night	12% 4 1 3 2 2 3 2 3 5% 61%	2280
	21st to end	Night	13% 6% 2 4 2 2 2 2 4 4 58%	2508
November	1st to 10th	Night	11% 6% 1 3 2 2 3 2 3 5% 62%	2340
	11th to 20th	Night	9% 5% 2 4 3 3 2 3 4 5% 60%	2585
	21st to end	Night	13% 6% 2 4 3 2 3 2 4 5% 56%	2600
December	1st to 10th	Night	9% 7% 2 4 3 3 3 2 4 5% 58%	4250
	11th to 20th	Night	15% 6% 2 5% 3 3 3 2 3 5% 54%	4816
	21st to end	Night	19% 10% 3 6% 3 3 3 2 4 5% 43%	6490

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	42% 4 10% 25% 18% 1	4078
	11th to 20th	Day	29% 3 11% 24% 27% 5%	4080
	21st to end	Day	42% 2 5% 20% 25% 4	4488
February	1st to 10th	Day	45% 3 10% 21% 16% 4	1800
	11th to 20th	Day	40% 5% 8% 26% 18% 4	1908
	21st to end	Day	40% 3 6% 21% 20% 9%	1686
March	1st to 10th	Day	34% 3 5% 21% 19% 18%	4936
	11th to 20th	Day	29% 5% 9% 20% 21% 16%	4980
	21st to end	Day	43% 6% 10% 28% 12% 1	5464
April	1st to 10th	Day	37% 5% 10% 23% 19% 6%	2205
	11th to 20th	Day	39% 5% 10% 22% 18% 6%	2374
	21st to end	Day	45% 5% 8% 23% 17% 2	2567
May	1st to 10th	Day	46% 6% 9% 21% 16% 2	5900
	11th to 20th	Day	35% 8% 11% 21% 21% 4	5866
	21st to end	Day	47% 8% 11% 16% 15% 3	6447
June	1st to 10th	Day	31% 9% 13% 27% 18% 3	2600
	11th to 20th	Day	34% 6% 13% 27% 17% 3	2600
	21st to end	Day	24% 6% 14% 29% 21% 5%	2600
July	1st to 10th	Day	31% 9% 17% 27% 14% 2	5836
	11th to 20th	Day	29% 8% 12% 27% 22% 2	5831
	21st to end	Day	22% 9% 18% 36% 15%	6240
August	1st to 10th	Day	22% 6% 13% 29% 25% 6%	4220
	11th to 20th	Day	28% 8% 20% 26% 17% 2	4210
	21st to end	Day	24% 7% 13% 38% 14% 4	4444
September	1st to 10th	Day	31% 5% 9% 23% 23% 9%	2169
	11th to 20th	Day	33% 7% 11% 21% 22% 6%	2090
	21st to end	Day	29% 4 8% 24% 29% 7%	2090
October	1st to 10th	Day	17% 3 7% 16% 43% 14%	3266
	11th to 20th	Day	16% 2 4 21% 41% 16%	3140
	21st to end	Day	27% 3 7% 28% 29% 7%	3428
November	1st to 10th	Day	29% 3 7% 26% 26% 8%	1958
	11th to 20th	Day	28% 3 8% 28% 25% 9%	1810
	21st to end	Day	33% 3 8% 25% 25% 5%	1800
December	1st to 10th	Day	32% 4 7% 35% 21% 1	2940
	11th to 20th	Day	36% 3 5% 25% 28% 4	3389
	21st to end	Day	53% 4 8% 21% 11% 3	4488
January	1st to 10th	Night	38% 4 11% 28% 16% 3	5888
	11th to 20th	Night	24% 4 13% 21% 32% 6%	5900
	21st to end	Night	39% 3 7% 18% 28% 4	6490
February	1st to 10th	Night	41% 3 11% 23% 19% 4	2600
	11th to 20th	Night	39% 3 7% 26% 20% 5%	2407
	21st to end	Night	36% 4 8% 18% 24% 10%	1942
March	1st to 10th	Night	37% 3 6% 19% 21% 13%	4919
	11th to 20th	Night	23% 3 7% 24% 25% 17%	4980
	21st to end	Night	34% 5% 12% 31% 16% 2	5467
April	1st to 10th	Night	32% 5% 10% 22% 23% 9%	2192
	11th to 20th	Night	34% 4 10% 24% 19% 9%	1975
	21st to end	Night	38% 4 9% 24% 21% 3	1830
May	1st to 10th	Night	40% 6% 11% 20% 20% 3	4080
	11th to 20th	Night	35% 6% 11% 22% 19% 7%	4054
	21st to end	Night	35% 6% 15% 23% 16% 4	4452
June	1st to 10th	Night	25% 8% 16% 29% 19% 3	1800
	11th to 20th	Night	23% 6% 14% 33% 21% 4	1800
	21st to end	Night	18% 5% 14% 30% 26% 7%	1800
July	1st to 10th	Night	26% 9% 19% 28% 15% 4	4035
	11th to 20th	Night	20% 7% 13% 34% 24% 2	4026
	21st to end	Night	17% 5% 15% 39% 22% 1	4320
August	1st to 10th	Night	16% 5% 13% 33% 26% 7%	2916
	11th to 20th	Night	26% 8% 17% 26% 20% 4	2915
	21st to end	Night	18% 6% 11% 41% 19% 5%	3455
September	1st to 10th	Night	27% 4 9% 25% 24% 11%	2073
	11th to 20th	Night	32% 6% 10% 20% 25% 7%	2090
	21st to end	Night	26% 4 8% 24% 31% 7%	2090
October	1st to 10th	Night	14% 3 6% 15% 37% 25%	3661
	11th to 20th	Night	19% 2 5% 18% 37% 18%	3779
	21st to end	Night	25% 4 7% 27% 28% 9%	4120
November	1st to 10th	Night	26% 3 8% 24% 30% 9%	2340
	11th to 20th	Night	28% 3 7% 24% 27% 10%	2585
	21st to end	Night	32% 3 7% 23% 28% 7%	2600
December	1st to 10th	Night	29% 4 10% 36% 19% 3	4250
	11th to 20th	Night	36% 3 5% 23% 26% 7%	4817
	21st to end	Night	45% 3 8% 25% 15% 5%	6490

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% 14% 37% 23% 4	300
	11th to 20th	Day	22% 19% 40% 16% 4	300
	21st to end	Day	17% 20% 37% 18% 8%	330
February	1st to 10th	Day	25% 16% 37% 18% 3	300
	11th to 20th	Day	24% 21% 38% 15% 2	300
	21st to end	Day	29% 19% 33% 17% 3	249
March	1st to 10th	Day	21% 22% 35% 19% 3	300
	11th to 20th	Day	19% 25% 38% 15% 3	300
	21st to end	Day	22% 26% 33% 16% 2 1	330
April	1st to 10th	Day	19% 27% 33% 16% 4 1	305
	11th to 20th	Day	22% 20% 36% 18% 4	492
	21st to end	Day	22% 20% 32% 17% 8% 1	667
May	1st to 10th	Day	15% 16% 37% 24% 6% 1	703
	11th to 20th	Day	18% 11% 32% 25% 11% 3	725
	21st to end	Day	17% 9% 32% 24% 12% 6%	789
June	1st to 10th	Day	8% 5% 24% 37% 22% 5%	730
	11th to 20th	Day	11% 2 25% 38% 20% 4	730
	21st to end	Day	4 3 25% 42% 22% 5%	730
July	1st to 10th	Day	8% 3 15% 33% 30% 12%	721
	11th to 20th	Day	4 2 16% 40% 32% 6%	718
	21st to end	Day	7% 1 12% 34% 34% 12%	794
August	1st to 10th	Day	6% 2 15% 43% 29% 5%	726
	11th to 20th	Day	9% 2 16% 37% 31% 6%	715
	21st to end	Day	9% 2 9% 35% 35% 9%	664
September	1st to 10th	Day	9% 2 14% 34% 28% 13%	355
	11th to 20th	Day	6% 2 17% 40% 28% 7%	300
	21st to end	Day	12% 5% 21% 34% 21% 6%	300
October	1st to 10th	Day	9% 6% 30% 30% 21% 4	300
	11th to 20th	Day	10% 12% 39% 29% 9% 1	300
	21st to end	Day	23% 14% 30% 24% 8% 2	330
November	1st to 10th	Day	15% 10% 39% 24% 10% 2	300
	11th to 20th	Day	16% 15% 35% 22% 10% 2	300
	21st to end	Day	24% 13% 38% 16% 8% 1	300
December	1st to 10th	Day	15% 17% 39% 18% 10% 1	300
	11th to 20th	Day	22% 16% 36% 20% 6%	300
	21st to end	Day	21% 21% 36% 19% 3	330
January	1st to 10th	Night	15% 13% 38% 28% 6%	1000
	11th to 20th	Night	16% 15% 38% 26% 5%	1000
	21st to end	Night	15% 14% 38% 28% 4	1100
February	1st to 10th	Night	21% 15% 36% 25% 4	1000
	11th to 20th	Night	19% 18% 34% 26% 3	852
	21st to end	Night	18% 16% 38% 26% 3	622
March	1st to 10th	Night	17% 14% 36% 30% 4	600
	11th to 20th	Night	20% 13% 38% 26% 4	600
	21st to end	Night	18% 13% 41% 22% 5%	660
April	1st to 10th	Night	15% 15% 40% 26% 3	600
	11th to 20th	Night	17% 14% 38% 25% 5%	593
	21st to end	Night	18% 12% 40% 23% 6% 1	600
May	1st to 10th	Night	15% 9% 41% 29% 6%	600
	11th to 20th	Night	14% 8% 31% 34% 14%	591
	21st to end	Night	12% 6% 30% 34% 16% 1	650
June	1st to 10th	Night	8% 4 23% 40% 25% 1	600
	11th to 20th	Night	6% 2 30% 43% 19% 1	600
	21st to end	Night	3 2 28% 49% 17% 2	600
July	1st to 10th	Night	6% 1 15% 44% 30% 3	585
	11th to 20th	Night	4 2 16% 47% 29% 3	582
	21st to end	Night	5% 1 14% 42% 35% 2	657
August	1st to 10th	Night	4 1 16% 49% 28% 2	597
	11th to 20th	Night	6% 2 14% 44% 31% 3	594
	21st to end	Night	4 1 15% 39% 37% 4	660
September	1st to 10th	Night	10% 2 13% 43% 31% 1	579
	11th to 20th	Night	12% 2 20% 40% 23% 4	570
	21st to end	Night	10% 3 21% 40% 24% 3	570
October	1st to 10th	Night	8% 3 29% 37% 21% 3	673
	11th to 20th	Night	13% 9% 36% 31% 10% 1	760
	21st to end	Night	16% 13% 30% 29% 11% 1	836
November	1st to 10th	Night	13% 8% 40% 27% 11%	780
	11th to 20th	Night	13% 14% 34% 30% 9%	985
	21st to end	Night	17% 13% 34% 27% 9%	1000
December	1st to 10th	Night	16% 14% 33% 29% 7% 1	1000
	11th to 20th	Night	20% 11% 35% 28% 6%	1000
	21st to end	Night	19% 15% 34% 26% 5%	1100

Page generated at 2025-09-01 00:51:07. Version ac07

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