Bartlesville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bartlesville clear sky chart from 2005-11-06 to 2025-05-11.

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% 49%	114554
	Night	11% 6% 2 5% 3 3 3 3 5% 6% 54%	114618
Transparency	Day	33% 6% 11% 25% 20% 5%	118246
	Night	30% 5% 10% 26% 23% 6%	119054
Seeing	Day	13% 9% 27% 29% 18% 4	16116
	Night	13% 9% 31% 33% 13% 1	26101

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% 8% 4 7% 4 3 3 3 4 6% 43%	4077
	11th to 20th	Day	7% 7% 2 7% 5% 4 4 3 4 5% 52%	4080
	21st to end	Day	15% 11% 3 5% 2 3 2 2 3 5% 48%	4488
February	1st to 10th	Day	15% 10% 3 7% 5% 4 3 3 3 6% 41%	1800
	11th to 20th	Day	13% 8% 3 7% 3 4 3 3 4 6% 47%	1881
	21st to end	Day	12% 9% 2 6% 4 3 4 3 5% 6% 46%	1680
March	1st to 10th	Day	11% 7% 2 5% 3 3 3 2 4 5% 54%	4936
	11th to 20th	Day	8% 6% 2 4 2 3 3 3 5% 6% 57%	4980
	21st to end	Day	12% 8% 3 7% 5% 5% 5% 4 6% 8% 37%	5462
April	1st to 10th	Day	11% 7% 2 6% 4 3 4 4 6% 7% 47%	2215
	11th to 20th	Day	14% 6% 2 6% 4 4 4 4 5% 8% 43%	2374
	21st to end	Day	19% 8% 2 7% 4 3 4 3 5% 6% 40%	2585
May	1st to 10th	Day	20% 8% 3 6% 3 4 4 3 4 5% 39%	4212
	11th to 20th	Day	11% 6% 2 6% 5% 4 5% 4 5% 8% 43%	4083
	21st to end	Day	13% 6% 3 7% 5% 5% 5% 4 6% 7% 40%	4477
June	1st to 10th	Day	6% 4 2 5% 4 5% 5% 4 7% 10% 47%	2470
	11th to 20th	Day	7% 4 2 6% 5% 4 5% 4 6% 7% 50%	2470
	21st to end	Day	6% 2 1 4 4 4 4 4 5% 8% 59%	2470
July	1st to 10th	Day	9% 6% 2 6% 5% 5% 5% 4 6% 9% 45%	4120
	11th to 20th	Day	5% 3 2 4 3 4 4 4 6% 9% 54%	4120
	21st to end	Day	5% 4 1 5% 4 4 4 5% 7% 11% 51%	4465
August	1st to 10th	Day	5% 3 1 4 3 3 3 3 6% 9% 58%	4104
	11th to 20th	Day	6% 4 2 6% 4 4 5% 4 7% 10% 48%	4041
	21st to end	Day	5% 4 1 5% 3 3 4 4 5% 8% 58%	4319
September	1st to 10th	Day	11% 4 1 5% 4 3 4 4 5% 5% 54%	2147
	11th to 20th	Day	10% 5% 2 5% 4 4 4 3 6% 7% 49%	2090
	21st to end	Day	8% 4 2 5% 3 3 3 3 5% 6% 59%	2090
October	1st to 10th	Day	10% 4 2 5% 3 3 3 3 6% 6% 56%	1962
	11th to 20th	Day	10% 4 2 4 2 3 2 2 4 5% 62%	1900
	21st to end	Day	14% 7% 2 4 2 3 3 2 3 6% 54%	2090
November	1st to 10th	Day	10% 6% 1 4 3 3 3 2 4 6% 59%	1947
	11th to 20th	Day	11% 5% 2 3 2 2 3 3 4 6% 60%	1800
	21st to end	Day	13% 6% 2 4 3 2 3 2 4 6% 55%	1800
December	1st to 10th	Day	10% 7% 2 5% 3 3 3 2 3 5% 57%	2940
	11th to 20th	Day	10% 6% 2 6% 4 3 4 3 3 5% 55%	3391
	21st to end	Day	19% 14% 5% 8% 4 4 3 3 4 5% 32%	4488
January	1st to 10th	Night	14% 7% 2 6% 4 3 3 3 5% 6% 47%	5888
	11th to 20th	Night	6% 5% 2 6% 4 4 4 3 5% 6% 56%	5900
	21st to end	Night	17% 8% 3 5% 3 3 2 2 3 4 51%	6490
February	1st to 10th	Night	14% 9% 2 6% 4 4 4 4 3 5% 45%	2600
	11th to 20th	Night	13% 8% 3 5% 4 3 3 3 4 5% 49%	2422
	21st to end	Night	13% 6% 2 5% 4 3 3 2 4 6% 53%	1950
March	1st to 10th	Night	12% 7% 2 5% 3 3 3 2 4 5% 53%	4919
	11th to 20th	Night	8% 4 2 4 2 2 3 3 4 7% 63%	4980
	21st to end	Night	11% 5% 2 5% 4 4 5% 3 5% 7% 48%	5467
April	1st to 10th	Night	12% 6% 2 4 3 3 3 3 5% 6% 53%	2185
	11th to 20th	Night	14% 5% 2 4 3 3 4 3 4 6% 52%	1975
	21st to end	Night	16% 6% 2 5% 4 2 3 3 5% 7% 47%	1811
May	1st to 10th	Night	17% 8% 2 6% 4 3 3 3 5% 6% 43%	2913
	11th to 20th	Night	15% 6% 2 5% 3 3 3 2 5% 6% 47%	2828
	21st to end	Night	10% 5% 2 4 3 3 3 3 7% 10% 49%	3090
June	1st to 10th	Night	5% 5% 2 5% 4 3 4 4 6% 9% 53%	1710
	11th to 20th	Night	5% 3 1 3 3 3 4 4 7% 11% 54%	1710
	21st to end	Night	4 3 1 3 3 3 3 3 5% 9% 63%	1710
July	1st to 10th	Night	7% 5% 2 5% 3 3 4 4 6% 9% 51%	2850
	11th to 20th	Night	3 2 2 4 3 3 3 4 4 9% 63%	2850
	21st to end	Night	5% 3 1 4 3 4 4 4 6% 10% 55%	3098
August	1st to 10th	Night	3 2 1 3 3 3 4 4 6% 10% 61%	2836
	11th to 20th	Night	4 4 2 5% 4 5% 6% 4 6% 9% 51%	2798
	21st to end	Night	3 2 1 3 3 3 3 3 5% 8% 65%	3339
September	1st to 10th	Night	9% 4 2 4 4 3 3 3 3 5% 61%	2029
	11th to 20th	Night	9% 5% 2 6% 3 4 4 3 6% 7% 51%	2090
	21st to end	Night	7% 3 1 5% 3 3 4 2 3 6% 62%	2090
October	1st to 10th	Night	8% 4 2 3 4 3 3 3 4 6% 61%	2197
	11th to 20th	Night	12% 4 2 3 2 2 3 2 3 5% 62%	2280
	21st to end	Night	13% 5% 2 5% 3 2 3 3 4 5% 56%	2508
November	1st to 10th	Night	10% 4 1 3 3 2 2 3 4 5% 62%	2349
	11th to 20th	Night	11% 5% 1 4 3 2 3 2 4 5% 59%	2600
	21st to end	Night	14% 5% 2 4 3 2 2 3 3 5% 57%	2600
December	1st to 10th	Night	8% 6% 2 4 3 3 3 3 4 5% 60%	4250
	11th to 20th	Night	12% 6% 2 5% 3 3 3 2 4 4 55%	4816
	21st to end	Night	19% 10% 4 6% 3 3 3 3 4 5% 41%	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	43% 4 11% 25% 16% 2	4078
	11th to 20th	Day	32% 4 14% 23% 21% 6%	4080
	21st to end	Day	41% 3 8% 21% 25% 3	4488
February	1st to 10th	Day	45% 4 11% 23% 14% 4	1800
	11th to 20th	Day	40% 4 10% 26% 17% 3	1890
	21st to end	Day	39% 4 7% 22% 19% 9%	1680
March	1st to 10th	Day	32% 3 6% 20% 21% 17%	4936
	11th to 20th	Day	28% 5% 9% 19% 23% 16%	4980
	21st to end	Day	42% 8% 11% 29% 9% 1	5464
April	1st to 10th	Day	35% 6% 11% 23% 19% 5%	2215
	11th to 20th	Day	39% 6% 13% 20% 16% 6%	2374
	21st to end	Day	45% 6% 9% 22% 15% 2	2585
May	1st to 10th	Day	46% 7% 9% 20% 15% 3	4250
	11th to 20th	Day	36% 10% 14% 22% 17% 1	4087
	21st to end	Day	39% 10% 15% 20% 14% 3	4489
June	1st to 10th	Day	28% 10% 18% 26% 16% 2	2470
	11th to 20th	Day	32% 7% 14% 27% 17% 3	2470
	21st to end	Day	22% 7% 15% 29% 22% 4	2470
July	1st to 10th	Day	33% 7% 16% 23% 17% 4	4056
	11th to 20th	Day	25% 6% 12% 33% 23% 2	4051
	21st to end	Day	24% 8% 19% 33% 15%	4325
August	1st to 10th	Day	23% 6% 14% 27% 25% 5%	4090
	11th to 20th	Day	29% 8% 20% 23% 18% 1	4080
	21st to end	Day	25% 7% 13% 38% 14% 4	4318
September	1st to 10th	Day	31% 7% 10% 22% 22% 9%	2147
	11th to 20th	Day	32% 8% 13% 23% 21% 4	2090
	21st to end	Day	27% 5% 10% 22% 29% 7%	2090
October	1st to 10th	Day	20% 4 7% 16% 41% 12%	3261
	11th to 20th	Day	16% 2 5% 25% 38% 14%	3140
	21st to end	Day	28% 3 7% 28% 28% 6%	3428
November	1st to 10th	Day	29% 4 8% 28% 25% 7%	1947
	11th to 20th	Day	26% 4 9% 26% 26% 8%	1800
	21st to end	Day	32% 4 9% 25% 26% 4	1800
December	1st to 10th	Day	33% 3 6% 38% 19% 1	2940
	11th to 20th	Day	33% 4 6% 28% 26% 3	3389
	21st to end	Day	54% 5% 8% 22% 9% 2	4488
January	1st to 10th	Night	37% 5% 11% 30% 14% 3	5888
	11th to 20th	Night	26% 6% 12% 22% 28% 6%	5900
	21st to end	Night	39% 3 8% 20% 26% 4	6490
February	1st to 10th	Night	42% 5% 11% 22% 17% 5%	2600
	11th to 20th	Night	37% 4 10% 26% 18% 4	2422
	21st to end	Night	34% 3 8% 20% 25% 9%	1950
March	1st to 10th	Night	34% 5% 6% 21% 22% 12%	4919
	11th to 20th	Night	22% 4 8% 23% 29% 15%	4980
	21st to end	Night	33% 7% 11% 32% 15% 2	5467
April	1st to 10th	Night	31% 6% 11% 22% 22% 9%	2185
	11th to 20th	Night	34% 5% 12% 22% 20% 8%	1975
	21st to end	Night	37% 6% 13% 22% 20% 3	1811
May	1st to 10th	Night	39% 8% 13% 18% 18% 4	2940
	11th to 20th	Night	38% 7% 12% 26% 16% 1	2829
	21st to end	Night	28% 9% 17% 25% 19% 1	3099
June	1st to 10th	Night	25% 9% 16% 30% 17% 3	1710
	11th to 20th	Night	21% 7% 16% 31% 22% 3	1710
	21st to end	Night	20% 6% 15% 31% 24% 5%	1710
July	1st to 10th	Night	28% 6% 16% 28% 18% 4	2805
	11th to 20th	Night	18% 5% 10% 36% 28% 3	2796
	21st to end	Night	23% 7% 17% 34% 18% 1	2999
August	1st to 10th	Night	16% 6% 16% 31% 23% 8%	2826
	11th to 20th	Night	28% 7% 17% 24% 20% 3	2825
	21st to end	Night	17% 6% 12% 40% 19% 5%	3339
September	1st to 10th	Night	27% 5% 9% 26% 23% 10%	2029
	11th to 20th	Night	33% 5% 12% 20% 24% 7%	2090
	21st to end	Night	24% 5% 8% 24% 31% 7%	2090
October	1st to 10th	Night	15% 3 6% 14% 41% 21%	3665
	11th to 20th	Night	19% 3 5% 20% 36% 18%	3779
	21st to end	Night	27% 4 7% 27% 28% 8%	4120
November	1st to 10th	Night	25% 4 9% 25% 29% 8%	2349
	11th to 20th	Night	28% 4 7% 25% 28% 8%	2600
	21st to end	Night	31% 4 9% 23% 27% 6%	2600
December	1st to 10th	Night	27% 4 10% 39% 17% 2	4250
	11th to 20th	Night	35% 3 6% 24% 26% 5%	4817
	21st to end	Night	45% 5% 9% 24% 13% 4	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	19% 15% 33% 28% 6%	300
	11th to 20th	Day	21% 16% 41% 18% 3	300
	21st to end	Day	16% 15% 40% 23% 5% 1	330
February	1st to 10th	Day	23% 17% 33% 23% 3	300
	11th to 20th	Day	19% 17% 42% 18% 3	300
	21st to end	Day	21% 18% 39% 18% 4	249
March	1st to 10th	Day	19% 18% 38% 20% 4	300
	11th to 20th	Day	24% 17% 38% 19% 3	300
	21st to end	Day	19% 21% 39% 16% 3 1	330
April	1st to 10th	Day	18% 20% 40% 17% 5%	315
	11th to 20th	Day	20% 18% 37% 21% 4	492
	21st to end	Day	22% 17% 32% 20% 8% 1	685
May	1st to 10th	Day	17% 13% 35% 26% 9%	703
	11th to 20th	Day	16% 8% 32% 28% 12% 3	676
	21st to end	Day	17% 8% 29% 23% 17% 6%	734
June	1st to 10th	Day	6% 4 21% 34% 29% 5%	680
	11th to 20th	Day	8% 3 24% 41% 20% 3	680
	21st to end	Day	4 3 27% 41% 21% 4	680
July	1st to 10th	Day	8% 2 15% 32% 31% 12%	671
	11th to 20th	Day	3 2 13% 40% 34% 8%	668
	21st to end	Day	6% 2 10% 34% 36% 12%	739
August	1st to 10th	Day	6% 1 14% 41% 32% 6%	676
	11th to 20th	Day	7% 2 14% 37% 34% 6%	665
	21st to end	Day	6% 1 11% 34% 39% 10%	626
September	1st to 10th	Day	9% 2 13% 28% 39% 10%	357
	11th to 20th	Day	5% 1 17% 41% 25% 11%	300
	21st to end	Day	12% 4 25% 33% 21% 6%	300
October	1st to 10th	Day	8% 6% 30% 29% 20% 7%	300
	11th to 20th	Day	8% 11% 44% 26% 12%	300
	21st to end	Day	22% 9% 33% 25% 8% 2	330
November	1st to 10th	Day	17% 10% 35% 27% 10% 1	300
	11th to 20th	Day	14% 16% 35% 21% 11% 2	300
	21st to end	Day	18% 16% 34% 22% 8% 1	300
December	1st to 10th	Day	13% 12% 45% 18% 9% 3	300
	11th to 20th	Day	18% 17% 35% 21% 8% 1	300
	21st to end	Day	18% 22% 37% 18% 4	330
January	1st to 10th	Night	14% 12% 38% 30% 7%	1000
	11th to 20th	Night	15% 14% 39% 27% 5%	1000
	21st to end	Night	13% 12% 40% 30% 4	1100
February	1st to 10th	Night	19% 14% 39% 25% 4	1000
	11th to 20th	Night	17% 16% 36% 28% 3	867
	21st to end	Night	16% 14% 37% 29% 4	630
March	1st to 10th	Night	15% 12% 39% 30% 5%	600
	11th to 20th	Night	18% 12% 37% 27% 7%	600
	21st to end	Night	18% 12% 42% 24% 4	660
April	1st to 10th	Night	15% 14% 41% 27% 4	600
	11th to 20th	Night	18% 12% 38% 25% 7%	593
	21st to end	Night	17% 11% 40% 25% 8%	600
May	1st to 10th	Night	14% 8% 39% 32% 7% 1	600
	11th to 20th	Night	14% 9% 26% 35% 15% 1	563
	21st to end	Night	9% 6% 30% 35% 19% 2	617
June	1st to 10th	Night	7% 2 21% 44% 26% 1	570
	11th to 20th	Night	5% 2 27% 46% 20% 1	570
	21st to end	Night	3 2 29% 46% 18% 1	570
July	1st to 10th	Night	7% 2 14% 45% 30% 3	555
	11th to 20th	Night	3 1 13% 47% 32% 3	552
	21st to end	Night	6% 2 11% 42% 36% 3	624
August	1st to 10th	Night	4 2 14% 48% 30% 2	567
	11th to 20th	Night	8% 1 14% 47% 28% 2	564
	21st to end	Night	3 2 11% 41% 42% 2	627
September	1st to 10th	Night	10% 1 16% 42% 29% 1	570
	11th to 20th	Night	12% 2 20% 40% 22% 4	570
	21st to end	Night	9% 4 21% 40% 23% 3	570
October	1st to 10th	Night	9% 2 28% 35% 23% 2	677
	11th to 20th	Night	14% 6% 38% 33% 9% 1	760
	21st to end	Night	15% 11% 33% 30% 10% 1	836
November	1st to 10th	Night	11% 7% 37% 31% 11% 1	789
	11th to 20th	Night	13% 12% 36% 30% 9% 1	1000
	21st to end	Night	17% 11% 33% 30% 9%	1000
December	1st to 10th	Night	15% 13% 34% 31% 7%	1000
	11th to 20th	Night	18% 11% 35% 30% 6%	1000
	21st to end	Night	18% 12% 36% 29% 5%	1100

Page generated at 2025-05-08 08:34:00. Version ac07

Copyright © 2025 Attilla Danko.