Buffalo
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Buffalo clear sky chart from 2005-11-06 to 2026-06-16.

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% 4 9% 5% 5% 4 4 5% 7% 30%	137932
	Night	17% 13% 4 10% 6% 5% 4 3 5% 6% 28%	134071
Transparency	Day	54% 3 12% 20% 10% 1	141526
	Night	57% 3 10% 18% 10% 1	138564
Seeing	Day	24% 17% 28% 19% 9% 3	16531
	Night	24% 15% 27% 24% 9% 1	25985

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% 21% 7% 15% 7% 6% 4 3 4 4 12%	4661
	11th to 20th	Day	11% 24% 8% 20% 11% 5% 5% 3 3 3 7%	5108
	21st to end	Day	15% 15% 7% 16% 11% 10% 6% 3 4 4 9%	5780
February	1st to 10th	Day	16% 19% 5% 14% 8% 6% 6% 3 4 5% 13%	1890
	11th to 20th	Day	14% 19% 7% 15% 8% 6% 5% 3 4 5% 16%	1843
	21st to end	Day	20% 15% 5% 12% 8% 4 5% 4 4 5% 17%	1637
March	1st to 10th	Day	17% 14% 6% 11% 6% 4 4 3 4 5% 26%	5042
	11th to 20th	Day	12% 17% 5% 8% 5% 5% 4 4 5% 7% 30%	5090
	21st to end	Day	21% 14% 4 9% 5% 4 4 3 5% 5% 26%	5586
April	1st to 10th	Day	19% 15% 4 7% 5% 4 4 3 4 5% 29%	2500
	11th to 20th	Day	19% 12% 3 8% 4 4 4 4 5% 5% 33%	2510
	21st to end	Day	21% 10% 3 7% 4 4 4 4 4 5% 33%	2730
May	1st to 10th	Day	22% 10% 3 7% 5% 4 5% 4 5% 7% 29%	7642
	11th to 20th	Day	18% 9% 3 8% 5% 4 4 4 5% 8% 32%	8178
	21st to end	Day	20% 7% 2 6% 3 4 4 4 6% 7% 38%	9060
June	1st to 10th	Day	16% 7% 2 6% 4 4 5% 4 6% 7% 39%	2940
	11th to 20th	Day	13% 5% 3 7% 5% 6% 5% 5% 7% 9% 38%	2870
	21st to end	Day	15% 6% 2 6% 4 4 4 4 7% 8% 42%	2800
July	1st to 10th	Day	10% 6% 2 6% 4 4 5% 4 6% 9% 44%	6360
	11th to 20th	Day	12% 6% 2 7% 4 5% 4 4 7% 9% 40%	6360
	21st to end	Day	9% 5% 2 6% 4 4 5% 4 6% 9% 45%	6472
August	1st to 10th	Day	17% 6% 2 5% 4 4 5% 4 5% 9% 38%	4234
	11th to 20th	Day	13% 6% 3 7% 5% 5% 6% 4 8% 10% 33%	4174
	21st to end	Day	12% 6% 2 6% 4 4 4 4 6% 9% 44%	4421
September	1st to 10th	Day	14% 7% 2 6% 4 5% 5% 3 6% 7% 42%	2400
	11th to 20th	Day	11% 5% 2 6% 3 5% 4 4 6% 8% 46%	2319
	21st to end	Day	16% 8% 3 7% 5% 5% 5% 4 6% 7% 32%	2135
October	1st to 10th	Day	20% 7% 3 7% 4 4 5% 3 5% 7% 36%	2000
	11th to 20th	Day	20% 10% 3 8% 5% 5% 5% 5% 5% 6% 28%	2000
	21st to end	Day	26% 13% 4 9% 5% 5% 4 4 4 5% 22%	2200
November	1st to 10th	Day	16% 11% 4 8% 6% 6% 4 3 5% 6% 31%	1836
	11th to 20th	Day	15% 14% 5% 9% 5% 6% 4 4 5% 6% 27%	1680
	21st to end	Day	21% 17% 4 9% 7% 5% 5% 3 5% 6% 18%	1680
December	1st to 10th	Day	20% 19% 5% 12% 6% 6% 5% 5% 5% 6% 12%	2680
	11th to 20th	Day	22% 20% 5% 10% 5% 4 3 3 4 5% 17%	3066
	21st to end	Day	23% 22% 6% 12% 6% 5% 4 3 3 4 12%	4048
January	1st to 10th	Night	17% 20% 7% 14% 7% 5% 3 3 4 5% 16%	8234
	11th to 20th	Night	12% 20% 8% 21% 10% 7% 4 3 3 3 9%	7759
	21st to end	Night	16% 18% 7% 16% 9% 8% 6% 3 4 4 9%	8401
February	1st to 10th	Night	18% 19% 6% 13% 7% 5% 4 3 4 4 17%	2730
	11th to 20th	Night	16% 16% 6% 12% 7% 5% 5% 4 4 5% 19%	2663
	21st to end	Night	18% 17% 5% 14% 7% 4 4 3 5% 5% 18%	2165
March	1st to 10th	Night	19% 12% 5% 9% 7% 4 4 3 4 4 28%	5018
	11th to 20th	Night	16% 14% 3 7% 4 4 4 3 5% 7% 33%	5089
	21st to end	Night	19% 12% 4 8% 4 4 4 3 5% 5% 33%	5588
April	1st to 10th	Night	22% 12% 4 8% 5% 4 4 3 5% 4 29%	2118
	11th to 20th	Night	19% 10% 3 7% 4 4 4 4 4 7% 34%	2075
	21st to end	Night	18% 9% 3 6% 4 4 5% 4 4 7% 35%	1892
May	1st to 10th	Night	26% 11% 4 8% 5% 4 3 4 4 5% 27%	5257
	11th to 20th	Night	16% 8% 3 7% 5% 5% 5% 4 6% 8% 33%	4680
	21st to end	Night	19% 8% 3 7% 4 3 4 4 5% 6% 37%	5114
June	1st to 10th	Night	12% 7% 3 7% 5% 5% 5% 5% 5% 8% 38%	1680
	11th to 20th	Night	13% 6% 2 5% 5% 5% 6% 5% 6% 8% 40%	1640
	21st to end	Night	15% 5% 2 6% 4 4 5% 3 6% 7% 41%	1600
July	1st to 10th	Night	11% 6% 2 7% 5% 4 4 4 6% 9% 42%	3600
	11th to 20th	Night	11% 6% 2 7% 5% 4 4 4 6% 8% 44%	3600
	21st to end	Night	10% 6% 2 5% 4 5% 4 4 6% 7% 49%	4376
August	1st to 10th	Night	11% 7% 2 7% 5% 4 4 3 6% 9% 41%	2915
	11th to 20th	Night	16% 7% 2 7% 4 5% 5% 4 6% 8% 38%	2875
	21st to end	Night	9% 5% 2 5% 5% 5% 5% 4 7% 9% 45%	3444
September	1st to 10th	Night	14% 6% 2 6% 4 3 4 3 5% 8% 44%	2000
	11th to 20th	Night	12% 5% 2 5% 3 3 3 3 4 8% 52%	2078
	21st to end	Night	17% 8% 2 6% 5% 4 5% 4 6% 7% 36%	2265
October	1st to 10th	Night	17% 6% 3 6% 5% 4 4 3 4 7% 40%	2400
	11th to 20th	Night	22% 10% 3 7% 4 5% 5% 3 5% 6% 30%	2400
	21st to end	Night	26% 9% 3 6% 5% 5% 4 4 5% 6% 27%	2640
November	1st to 10th	Night	18% 9% 3 7% 4 4 4 3 5% 6% 37%	2677
	11th to 20th	Night	16% 13% 4 9% 6% 5% 5% 3 5% 6% 28%	2940
	21st to end	Night	19% 17% 4 9% 5% 5% 5% 5% 5% 5% 21%	2940
December	1st to 10th	Night	18% 21% 7% 13% 6% 5% 5% 3 5% 5% 12%	4720
	11th to 20th	Night	21% 22% 5% 10% 6% 5% 4 3 4 4 17%	5348
	21st to end	Night	25% 18% 5% 11% 6% 5% 5% 3 4 4 13%	7150

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	78% 2 8% 8% 4	4662
	11th to 20th	Day	83% 2 4 5% 4 1	5142
	21st to end	Day	82% 2 10% 5% 2	5780
February	1st to 10th	Day	74% 5% 9% 11% 1	1890
	11th to 20th	Day	73% 4 9% 12% 2	1852
	21st to end	Day	69% 4 11% 11% 5%	1637
March	1st to 10th	Day	61% 2 13% 16% 8%	5045
	11th to 20th	Day	54% 3 19% 16% 7% 1	5090
	21st to end	Day	60% 4 6% 21% 8% 1	5586
April	1st to 10th	Day	57% 4 11% 18% 9% 1	2500
	11th to 20th	Day	53% 4 9% 20% 12% 2	2510
	21st to end	Day	53% 4 10% 19% 12% 2	2730
May	1st to 10th	Day	55% 3 10% 20% 9% 3	7651
	11th to 20th	Day	52% 3 11% 22% 11% 1	8182
	21st to end	Day	46% 2 11% 25% 13% 2	9061
June	1st to 10th	Day	43% 6% 12% 21% 17% 2	2940
	11th to 20th	Day	43% 6% 14% 24% 13% 1	2870
	21st to end	Day	40% 5% 14% 25% 15% 1	2800
July	1st to 10th	Day	38% 3 13% 28% 17% 1	6290
	11th to 20th	Day	42% 3 13% 27% 15% 1	6285
	21st to end	Day	35% 4 16% 27% 18% 1	6286
August	1st to 10th	Day	44% 5% 14% 23% 13% 1	4221
	11th to 20th	Day	45% 5% 15% 25% 9% 1	4213
	21st to end	Day	37% 4 12% 35% 12% 1	4421
September	1st to 10th	Day	40% 6% 13% 27% 12% 1	2400
	11th to 20th	Day	36% 5% 14% 31% 14% 1	2319
	21st to end	Day	49% 5% 14% 22% 9% 1	2135
October	1st to 10th	Day	41% 3 13% 27% 15% 1	3260
	11th to 20th	Day	47% 3 16% 21% 12% 1	3240
	21st to end	Day	53% 2 14% 23% 8% 1	3538
November	1st to 10th	Day	54% 5% 11% 20% 9% 1	1836
	11th to 20th	Day	57% 5% 14% 15% 7% 1	1680
	21st to end	Day	66% 5% 13% 12% 4	1680
December	1st to 10th	Day	73% 3 16% 7% 2	2680
	11th to 20th	Day	70% 3 10% 10% 7%	3066
	21st to end	Day	79% 2 9% 7% 3	4048
January	1st to 10th	Night	74% 2 9% 12% 3	8234
	11th to 20th	Night	79% 4 5% 6% 6%	7800
	21st to end	Night	80% 2 6% 7% 5%	8401
February	1st to 10th	Night	70% 5% 8% 12% 4	2730
	11th to 20th	Night	66% 5% 11% 14% 4	2665
	21st to end	Night	68% 4 10% 12% 6%	2165
March	1st to 10th	Night	60% 2 11% 17% 8% 1	5028
	11th to 20th	Night	51% 3 15% 20% 8% 2	5090
	21st to end	Night	53% 4 7% 21% 13% 1	5588
April	1st to 10th	Night	58% 4 8% 18% 10% 1	2118
	11th to 20th	Night	51% 4 10% 19% 13% 2	2075
	21st to end	Night	49% 4 10% 21% 14% 2	1892
May	1st to 10th	Night	60% 3 7% 16% 11% 4	5264
	11th to 20th	Night	49% 4 13% 20% 13% 1	4681
	21st to end	Night	48% 3 9% 22% 17% 2	5115
June	1st to 10th	Night	44% 6% 9% 23% 17% 2	1680
	11th to 20th	Night	40% 5% 13% 22% 18% 2	1640
	21st to end	Night	42% 5% 13% 22% 16% 2	1600
July	1st to 10th	Night	39% 3 12% 25% 19% 2	3560
	11th to 20th	Night	39% 3 13% 29% 15% 1	3552
	21st to end	Night	35% 3 14% 25% 22% 1	4247
August	1st to 10th	Night	40% 4 15% 27% 13% 2	2904
	11th to 20th	Night	45% 4 14% 27% 10%	2902
	21st to end	Night	36% 3 13% 33% 14% 1	3444
September	1st to 10th	Night	38% 5% 14% 28% 14% 1	2000
	11th to 20th	Night	33% 4 12% 33% 18% 1	2078
	21st to end	Night	46% 6% 13% 22% 13% 1	2265
October	1st to 10th	Night	44% 3 7% 26% 19% 1	3920
	11th to 20th	Night	50% 3 12% 21% 13% 1	3899
	21st to end	Night	48% 3 15% 25% 9% 1	4252
November	1st to 10th	Night	48% 5% 10% 24% 11% 2	2677
	11th to 20th	Night	57% 5% 13% 17% 8% 1	2940
	21st to end	Night	62% 6% 14% 15% 3	2940
December	1st to 10th	Night	74% 3 13% 9% 2	4720
	11th to 20th	Night	70% 3 7% 11% 8% 1	5348
	21st to end	Night	75% 3 10% 9% 3	7150

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	27% 30% 27% 10% 4 1	220
	11th to 20th	Day	30% 29% 27% 10% 4 1	305
	21st to end	Day	28% 26% 26% 16% 3	363
February	1st to 10th	Day	32% 25% 28% 12% 2	330
	11th to 20th	Day	32% 31% 28% 8% 1	330
	21st to end	Day	39% 21% 29% 10% 1	336
March	1st to 10th	Day	29% 21% 30% 15% 4 1	540
	11th to 20th	Day	34% 16% 31% 14% 4 1	540
	21st to end	Day	32% 20% 25% 16% 5% 1	594
April	1st to 10th	Day	28% 22% 28% 15% 5% 1	540
	11th to 20th	Day	34% 20% 22% 15% 6% 2	532
	21st to end	Day	30% 17% 29% 16% 7% 1	540
May	1st to 10th	Day	28% 16% 30% 15% 7% 3	543
	11th to 20th	Day	23% 14% 31% 19% 10% 3	567
	21st to end	Day	20% 14% 32% 21% 9% 4	617
June	1st to 10th	Day	22% 14% 34% 21% 7% 1	570
	11th to 20th	Day	16% 17% 31% 23% 10% 3	550
	21st to end	Day	20% 15% 31% 25% 8% 2	530
July	1st to 10th	Day	11% 10% 27% 31% 17% 4	525
	11th to 20th	Day	16% 11% 30% 26% 13% 5%	524
	21st to end	Day	11% 9% 35% 28% 12% 5%	576
August	1st to 10th	Day	15% 8% 23% 30% 16% 8%	526
	11th to 20th	Day	13% 8% 28% 26% 16% 8%	519
	21st to end	Day	15% 8% 32% 23% 15% 7%	583
September	1st to 10th	Day	16% 13% 23% 23% 17% 8%	530
	11th to 20th	Day	11% 7% 21% 25% 24% 13%	530
	21st to end	Day	18% 15% 28% 22% 12% 6%	530
October	1st to 10th	Day	24% 11% 26% 20% 14% 5%	530
	11th to 20th	Day	26% 20% 29% 18% 5% 2	530
	21st to end	Day	35% 19% 24% 15% 7%	583
November	1st to 10th	Day	27% 21% 29% 16% 6% 1	376
	11th to 20th	Day	34% 24% 27% 10% 3 2	220
	21st to end	Day	35% 28% 25% 10% 2	220
December	1st to 10th	Day	33% 24% 29% 10% 4	220
	11th to 20th	Day	35% 26% 25% 13% 2	220
	21st to end	Day	36% 29% 21% 10% 2 1	242
January	1st to 10th	Night	31% 25% 28% 13% 4	840
	11th to 20th	Night	33% 24% 25% 15% 3	840
	21st to end	Night	26% 23% 31% 16% 5%	924
February	1st to 10th	Night	27% 25% 28% 16% 2	840
	11th to 20th	Night	27% 23% 30% 17% 3	823
	21st to end	Night	29% 22% 29% 17% 2	692
March	1st to 10th	Night	25% 19% 31% 21% 5%	840
	11th to 20th	Night	29% 17% 30% 19% 5%	840
	21st to end	Night	26% 14% 31% 21% 7% 1	924
April	1st to 10th	Night	27% 16% 32% 21% 3	840
	11th to 20th	Night	25% 16% 28% 23% 7% 1	831
	21st to end	Night	23% 9% 31% 29% 8%	632
May	1st to 10th	Night	23% 10% 23% 30% 11% 2	630
	11th to 20th	Night	16% 8% 32% 36% 8%	430
	21st to end	Night	16% 10% 25% 33% 14% 1	455
June	1st to 10th	Night	14% 8% 31% 35% 12%	420
	11th to 20th	Night	15% 10% 29% 34% 12%	410
	21st to end	Night	17% 7% 33% 32% 11%	400
July	1st to 10th	Night	10% 5% 26% 42% 16% 1	390
	11th to 20th	Night	12% 7% 28% 33% 19% 1	388
	21st to end	Night	13% 4 25% 39% 18% 2	631
August	1st to 10th	Night	12% 4 20% 40% 23% 2	597
	11th to 20th	Night	11% 6% 20% 34% 26% 3	594
	21st to end	Night	14% 5% 24% 32% 23% 2	790
September	1st to 10th	Night	17% 8% 22% 33% 18% 3	800
	11th to 20th	Night	14% 5% 21% 30% 27% 5%	800
	21st to end	Night	20% 10% 24% 28% 16% 3	800
October	1st to 10th	Night	19% 10% 27% 26% 16% 2	800
	11th to 20th	Night	28% 15% 25% 23% 8% 1	800
	21st to end	Night	32% 14% 27% 23% 4	880
November	1st to 10th	Night	25% 16% 27% 23% 9% 1	820
	11th to 20th	Night	25% 21% 28% 17% 8% 1	840
	21st to end	Night	28% 22% 28% 16% 5%	840
December	1st to 10th	Night	34% 23% 23% 15% 4	840
	11th to 20th	Night	30% 27% 24% 15% 3	840
	21st to end	Night	35% 20% 27% 16% 2	924

Page generated at 2026-06-13 02:31:42. Version ac07

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