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 2024-01-31.

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	17% 11% 4 7% 6% 4 5% 5% 5% 7% 30%	74824
	Night	18% 11% 4 8% 6% 3 5% 4 5% 6% 29%	75297
Transparency	Day	53% 5% 13% 19% 9% 1	74539
	Night	56% 5% 11% 18% 9% 1	75116
Seeing	Day	23% 17% 28% 20% 9% 3	13453
	Night	23% 15% 27% 24% 10% 1	23006

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	18% 18% 7% 12% 10% 6% 5% 3 4 5% 12%	1517
	11th to 20th	Day	19% 19% 7% 13% 9% 4 5% 4 3 5% 13%	1667
	21st to end	Day	15% 19% 7% 14% 11% 6% 7% 5% 4 4 10%	1872
February	1st to 10th	Day	18% 18% 7% 13% 9% 4 7% 4 4 4 12%	1620
	11th to 20th	Day	14% 17% 7% 14% 9% 5% 5% 3 4 5% 16%	1573
	21st to end	Day	21% 14% 6% 11% 9% 3 5% 5% 4 5% 17%	1400
March	1st to 10th	Day	17% 12% 6% 11% 9% 3 5% 4 5% 5% 23%	1977
	11th to 20th	Day	15% 16% 5% 7% 6% 4 4 3 5% 7% 29%	1980
	21st to end	Day	20% 13% 5% 7% 7% 2 6% 4 5% 5% 27%	2178
April	1st to 10th	Day	18% 14% 4 7% 5% 3 4 5% 4 5% 30%	2142
	11th to 20th	Day	19% 9% 3 6% 4 2 5% 5% 5% 5% 36%	2147
	21st to end	Day	21% 10% 4 6% 5% 3 4 4 4 5% 33%	2340
May	1st to 10th	Day	17% 10% 3 6% 6% 3 5% 4 5% 7% 33%	2340
	11th to 20th	Day	16% 7% 3 6% 6% 3 5% 5% 5% 7% 36%	2462
	21st to end	Day	13% 6% 2 6% 4 3 4 5% 6% 8% 43%	2725
June	1st to 10th	Day	16% 6% 2 6% 5% 3 5% 5% 6% 8% 39%	2520
	11th to 20th	Day	13% 5% 3 5% 5% 4 5% 5% 6% 9% 40%	2520
	21st to end	Day	15% 6% 2 5% 4 3 4 4 5% 9% 43%	2520
July	1st to 10th	Day	9% 4 2 4 4 3 5% 5% 7% 9% 47%	2520
	11th to 20th	Day	13% 5% 3 6% 5% 4 5% 6% 8% 10% 37%	2520
	21st to end	Day	10% 6% 3 6% 5% 3 6% 6% 7% 10% 37%	2567
August	1st to 10th	Day	10% 5% 2 4 6% 4 5% 6% 7% 10% 41%	2327
	11th to 20th	Day	10% 6% 3 5% 6% 4 5% 6% 7% 10% 37%	2303
	21st to end	Day	13% 5% 2 5% 5% 3 4 5% 6% 9% 43%	2440
September	1st to 10th	Day	16% 6% 3 5% 5% 4 5% 4 6% 7% 41%	2160
	11th to 20th	Day	12% 5% 2 5% 4 4 4 5% 6% 8% 44%	2088
	21st to end	Day	16% 7% 3 6% 6% 4 6% 5% 6% 7% 34%	1922
October	1st to 10th	Day	22% 7% 4 6% 5% 3 4 5% 5% 7% 33%	1800
	11th to 20th	Day	21% 10% 4 7% 6% 4 5% 6% 5% 6% 27%	1800
	21st to end	Day	27% 14% 4 8% 6% 4 4 4 3 5% 21%	1980
November	1st to 10th	Day	15% 11% 5% 7% 7% 4 5% 4 4 6% 32%	1659
	11th to 20th	Day	16% 13% 5% 8% 5% 4 4 5% 5% 6% 28%	1520
	21st to end	Day	22% 17% 4 8% 7% 4 5% 4 4 7% 19%	1520
December	1st to 10th	Day	21% 18% 7% 10% 7% 4 5% 5% 4 5% 14%	1520
	11th to 20th	Day	21% 21% 6% 10% 8% 3 4 4 5% 5% 13%	1906
	21st to end	Day	27% 24% 6% 10% 6% 3 4 3 3 3 11%	2772
January	1st to 10th	Night	19% 20% 7% 11% 8% 4 5% 3 3 4 16%	2649
	11th to 20th	Night	20% 20% 7% 11% 8% 4 5% 4 4 4 12%	2508
	21st to end	Night	16% 18% 8% 12% 10% 4 5% 4 5% 4 14%	2711
February	1st to 10th	Night	20% 17% 8% 12% 8% 4 5% 3 4 4 16%	2340
	11th to 20th	Night	17% 15% 6% 10% 8% 4 5% 5% 4 5% 19%	2273
	21st to end	Night	21% 15% 6% 12% 8% 3 5% 4 4 5% 19%	1852
March	1st to 10th	Night	15% 13% 5% 9% 8% 3 5% 4 4 6% 27%	1970
	11th to 20th	Night	19% 12% 4 7% 5% 3 5% 4 4 5% 31%	1979
	21st to end	Night	18% 12% 4 8% 5% 3 4 4 5% 5% 32%	2178
April	1st to 10th	Night	21% 11% 4 7% 6% 2 4 5% 5% 4 31%	1816
	11th to 20th	Night	19% 9% 3 7% 5% 3 4 5% 4 7% 35%	1775
	21st to end	Night	19% 8% 4 5% 5% 2 6% 5% 4 7% 35%	1622
May	1st to 10th	Night	18% 8% 3 6% 5% 3 5% 5% 6% 7% 34%	1620
	11th to 20th	Night	14% 4 3 6% 7% 4 6% 4 6% 9% 38%	1429
	21st to end	Night	12% 5% 2 5% 4 3 5% 5% 6% 7% 44%	1550
June	1st to 10th	Night	12% 6% 3 6% 6% 5% 6% 6% 5% 8% 37%	1440
	11th to 20th	Night	13% 5% 2 5% 5% 3 6% 5% 5% 8% 42%	1440
	21st to end	Night	14% 5% 2 5% 5% 3 5% 4 6% 7% 42%	1440
July	1st to 10th	Night	7% 5% 3 6% 5% 3 5% 3 6% 8% 50%	1440
	11th to 20th	Night	11% 6% 3 4 5% 3 4 4 8% 8% 45%	1440
	21st to end	Night	11% 5% 2 5% 5% 4 5% 5% 7% 7% 44%	1747
August	1st to 10th	Night	9% 6% 2 4 6% 3 5% 5% 7% 10% 44%	1611
	11th to 20th	Night	12% 5% 2 5% 5% 3 5% 5% 6% 9% 44%	1598
	21st to end	Night	10% 5% 2 5% 5% 4 5% 5% 5% 7% 45%	1898
September	1st to 10th	Night	15% 6% 3 5% 5% 2 4 5% 5% 8% 43%	1800
	11th to 20th	Night	13% 5% 2 4 4 2 4 4 4 7% 51%	1870
	21st to end	Night	16% 7% 2 5% 6% 3 5% 5% 6% 7% 37%	2038
October	1st to 10th	Night	19% 7% 3 6% 6% 3 4 4 4 8% 38%	2160
	11th to 20th	Night	22% 9% 3 6% 6% 4 5% 4 5% 6% 29%	2160
	21st to end	Night	28% 9% 4 6% 5% 4 5% 4 5% 6% 24%	2376
November	1st to 10th	Night	18% 9% 3 6% 5% 3 4 4 5% 6% 37%	2415
	11th to 20th	Night	17% 11% 4 8% 7% 4 5% 4 5% 6% 29%	2660
	21st to end	Night	19% 15% 5% 9% 6% 3 5% 5% 5% 6% 22%	2660
December	1st to 10th	Night	22% 18% 6% 9% 7% 3 5% 4 5% 5% 15%	2660
	11th to 20th	Night	19% 21% 6% 10% 7% 4 4 4 4 4 17%	3288
	21st to end	Night	30% 16% 6% 9% 6% 3 5% 4 4 5% 11%	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	76% 4 8% 10% 2	1518
	11th to 20th	Day	75% 5% 10% 7% 2	1667
	21st to end	Day	79% 5% 8% 6% 2	1872
February	1st to 10th	Day	75% 5% 9% 9% 1	1620
	11th to 20th	Day	72% 4 8% 13% 3	1582
	21st to end	Day	70% 4 11% 9% 5%	1400
March	1st to 10th	Day	63% 5% 12% 14% 5% 1	1980
	11th to 20th	Day	56% 5% 12% 16% 9% 1	1980
	21st to end	Day	59% 5% 7% 19% 9% 2	2178
April	1st to 10th	Day	56% 4 11% 19% 9% 1	2142
	11th to 20th	Day	50% 4 10% 20% 14% 2	2147
	21st to end	Day	54% 4 9% 19% 12% 2	2340
May	1st to 10th	Day	50% 5% 10% 22% 11% 2	2340
	11th to 20th	Day	47% 6% 11% 22% 12% 2	2466
	21st to end	Day	38% 6% 16% 24% 13% 2	2725
June	1st to 10th	Day	42% 6% 14% 20% 16% 2	2520
	11th to 20th	Day	41% 6% 14% 24% 13% 1	2520
	21st to end	Day	39% 6% 14% 25% 15% 1	2520
July	1st to 10th	Day	32% 7% 14% 26% 19% 2	2450
	11th to 20th	Day	40% 7% 16% 24% 13%	2445
	21st to end	Day	40% 8% 17% 22% 12% 1	2423
August	1st to 10th	Day	37% 7% 17% 26% 11% 1	2314
	11th to 20th	Day	41% 7% 17% 24% 10% 1	2303
	21st to end	Day	37% 6% 15% 27% 12% 2	2440
September	1st to 10th	Day	41% 7% 13% 25% 12% 1	2160
	11th to 20th	Day	37% 5% 14% 28% 14% 1	2088
	21st to end	Day	47% 6% 14% 23% 10% 1	1922
October	1st to 10th	Day	51% 5% 14% 18% 11% 1	1800
	11th to 20th	Day	56% 6% 15% 17% 6% 1	1800
	21st to end	Day	67% 4 10% 13% 5% 1	1980
November	1st to 10th	Day	53% 6% 12% 19% 9% 1	1659
	11th to 20th	Day	57% 6% 16% 14% 6% 1	1520
	21st to end	Day	66% 5% 13% 12% 4	1520
December	1st to 10th	Day	72% 4 13% 9% 1	1520
	11th to 20th	Day	73% 5% 11% 9% 2	1906
	21st to end	Day	80% 3 10% 6% 1	2772
January	1st to 10th	Night	73% 5% 9% 9% 4	2649
	11th to 20th	Night	77% 5% 9% 7% 3	2508
	21st to end	Night	74% 5% 9% 9% 3 1	2711
February	1st to 10th	Night	72% 6% 8% 11% 4	2340
	11th to 20th	Night	67% 5% 11% 13% 4	2275
	21st to end	Night	68% 4 10% 13% 6%	1852
March	1st to 10th	Night	58% 5% 12% 18% 6% 1	1980
	11th to 20th	Night	56% 4 10% 19% 10% 1	1980
	21st to end	Night	55% 5% 7% 19% 13% 2	2178
April	1st to 10th	Night	56% 5% 8% 19% 11% 1	1816
	11th to 20th	Night	50% 5% 10% 20% 14% 2	1775
	21st to end	Night	50% 5% 10% 19% 14% 2	1622
May	1st to 10th	Night	48% 6% 9% 20% 13% 3	1620
	11th to 20th	Night	43% 7% 10% 23% 14% 2	1430
	21st to end	Night	37% 7% 14% 22% 17% 3	1551
June	1st to 10th	Night	44% 7% 10% 21% 16% 1	1440
	11th to 20th	Night	39% 6% 12% 22% 19% 2	1440
	21st to end	Night	41% 6% 13% 24% 15% 2	1440
July	1st to 10th	Night	32% 6% 12% 27% 19% 4	1400
	11th to 20th	Night	36% 5% 15% 28% 14% 2	1392
	21st to end	Night	36% 7% 15% 23% 16% 2	1650
August	1st to 10th	Night	34% 6% 17% 28% 14% 1	1600
	11th to 20th	Night	37% 6% 15% 29% 13% 1	1598
	21st to end	Night	37% 6% 13% 29% 13% 2	1898
September	1st to 10th	Night	39% 6% 15% 26% 14% 2	1800
	11th to 20th	Night	34% 4 12% 30% 18% 1	1870
	21st to end	Night	43% 6% 14% 23% 14% 1	2038
October	1st to 10th	Night	47% 5% 11% 21% 15% 1	2160
	11th to 20th	Night	56% 5% 13% 17% 9% 1	2160
	21st to end	Night	62% 4 12% 14% 8% 1	2376
November	1st to 10th	Night	48% 6% 10% 23% 11% 2	2415
	11th to 20th	Night	56% 5% 13% 17% 8% 1	2660
	21st to end	Night	62% 7% 14% 15% 3	2660
December	1st to 10th	Night	71% 5% 12% 10% 2	2660
	11th to 20th	Night	71% 5% 10% 11% 3	3288
	21st to end	Night	77% 3 11% 7% 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	28% 30% 23% 12% 5% 2	180
	11th to 20th	Day	27% 30% 26% 12% 4 1	249
	21st to end	Day	27% 24% 26% 19% 4	294
February	1st to 10th	Day	32% 29% 31% 7% 1	240
	11th to 20th	Day	29% 33% 28% 8% 1	240
	21st to end	Day	40% 19% 29% 11% 1	252
March	1st to 10th	Day	26% 22% 31% 16% 5%	420
	11th to 20th	Day	30% 16% 34% 16% 4 1	420
	21st to end	Day	32% 19% 27% 16% 5% 2	462
April	1st to 10th	Day	25% 23% 28% 17% 6% 1	420
	11th to 20th	Day	30% 21% 23% 16% 8% 3	412
	21st to end	Day	29% 17% 30% 15% 7% 2	420
May	1st to 10th	Day	27% 16% 29% 16% 7% 4	423
	11th to 20th	Day	21% 14% 30% 21% 9% 3	447
	21st to end	Day	18% 12% 31% 24% 11% 5%	485
June	1st to 10th	Day	21% 15% 34% 21% 8% 1	450
	11th to 20th	Day	17% 15% 30% 25% 10% 3	450
	21st to end	Day	20% 14% 31% 24% 9% 2	450
July	1st to 10th	Day	10% 10% 25% 31% 19% 4	445
	11th to 20th	Day	16% 12% 28% 25% 13% 5%	444
	21st to end	Day	13% 10% 34% 28% 11% 4	488
August	1st to 10th	Day	13% 9% 24% 30% 16% 8%	446
	11th to 20th	Day	12% 8% 28% 26% 17% 8%	439
	21st to end	Day	14% 8% 31% 24% 15% 8%	495
September	1st to 10th	Day	16% 12% 24% 26% 15% 7%	450
	11th to 20th	Day	13% 8% 22% 26% 22% 10%	450
	21st to end	Day	19% 16% 26% 21% 12% 6%	450
October	1st to 10th	Day	26% 12% 24% 18% 14% 6%	450
	11th to 20th	Day	27% 22% 27% 18% 5% 1	450
	21st to end	Day	37% 19% 24% 14% 6%	495
November	1st to 10th	Day	26% 19% 30% 17% 7% 1	319
	11th to 20th	Day	33% 26% 26% 10% 2 3	180
	21st to end	Day	33% 28% 24% 11% 3	180
December	1st to 10th	Day	32% 26% 30% 8% 4 1	180
	11th to 20th	Day	33% 28% 23% 14% 2	180
	21st to end	Day	35% 30% 23% 10% 2 1	198
January	1st to 10th	Night	32% 24% 26% 13% 4	760
	11th to 20th	Night	32% 24% 26% 15% 3	760
	21st to end	Night	25% 21% 31% 17% 6%	835
February	1st to 10th	Night	28% 27% 29% 13% 2	720
	11th to 20th	Night	26% 23% 30% 17% 3	703
	21st to end	Night	30% 23% 28% 17% 2	592
March	1st to 10th	Night	23% 18% 31% 22% 6%	720
	11th to 20th	Night	27% 17% 30% 21% 5% 1	720
	21st to end	Night	24% 13% 30% 23% 8% 1	792
April	1st to 10th	Night	25% 17% 32% 23% 3	720
	11th to 20th	Night	23% 17% 29% 23% 8% 1	711
	21st to end	Night	24% 8% 31% 28% 9%	542
May	1st to 10th	Night	21% 11% 23% 32% 12% 2	540
	11th to 20th	Night	16% 8% 31% 38% 7%	368
	21st to end	Night	14% 10% 25% 33% 16% 1	389
June	1st to 10th	Night	14% 8% 32% 33% 13% 1	360
	11th to 20th	Night	15% 10% 28% 35% 12%	360
	21st to end	Night	16% 8% 33% 32% 11%	360
July	1st to 10th	Night	10% 5% 25% 41% 18% 1	350
	11th to 20th	Night	12% 7% 28% 33% 18% 1	348
	21st to end	Night	13% 4 26% 39% 16% 2	567
August	1st to 10th	Night	11% 4 20% 39% 23% 2	537
	11th to 20th	Night	10% 6% 21% 34% 26% 3	534
	21st to end	Night	13% 5% 25% 32% 22% 2	710
September	1st to 10th	Night	18% 8% 21% 33% 18% 3	720
	11th to 20th	Night	15% 5% 23% 28% 24% 5%	720
	21st to end	Night	19% 11% 24% 27% 16% 4	720
October	1st to 10th	Night	20% 11% 27% 24% 16% 2	720
	11th to 20th	Night	28% 16% 25% 22% 8% 1	720
	21st to end	Night	34% 14% 26% 22% 4	792
November	1st to 10th	Night	24% 16% 27% 24% 9% 1	740
	11th to 20th	Night	24% 22% 29% 16% 8% 1	760
	21st to end	Night	28% 22% 28% 17% 5%	760
December	1st to 10th	Night	35% 23% 22% 15% 4	760
	11th to 20th	Night	29% 27% 25% 16% 3	760
	21st to end	Night	35% 20% 28% 16% 2	836

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